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Scheme of work · Cambridge International AS and A Level Mathematics 9709

A Level Maths scheme of work

93 lessons in 32 topics, in syllabus order: 69 hours 45 minutes of teaching at 45 minutes a lesson. Set your lessons per week and the week numbers follow. Every lesson links to its pack, every topic to its lab, question bank and notes.

Lesson packs
31 weeks for the course at 3 a weekRemembered in this browser.
At a glance

The course in numbers

Lessons
93, one 45-minute lesson pack each
Teaching time
69 hours 45 minutes
Weeks
31 at 3 lessons a week
Topics
32, in syllabus order
Assessment points
32 topic question banks, assignable in the app
Labs
The lessons embed their simulations

How to read it. One row is one 45-minute lesson; its pack holds the plan, worksheet and quiz. The week column counts 3 lessons a week until you change the control above; the sheet you download uses the same numbers. Each topic ends at an assessment point, its question bank, which you can assign in the app for a marked score. The learning intention is the first idea of each lesson in the students' own pages; the traps are the examiner traps those pages pre-empt.

Topic 01

Pure Mathematics 1

Weeks 1 to 9

1.1Quadratics

Weeks 1 to 2
WeekRefLessonLearning intention
11.1Completing the squareIn the lab, press Make the square and watch \(x^{2} + bx\) rearranged into a square: there is always a small corner missing, of area \(\left(\frac{b}{2}\right)^{2}\).
11.1The discriminantThe quadratic formula \(x = \dfrac{-b \pm \sqrt{b^{2} - 4ac}}{2a}\) only gives real answers when the number under the root is not negative.
11.1Quadratic equations and inequalitiesIn the lab, pick a quadratic and solve it by factorising, then by the formula, and check that both routes land on the same roots.
21.1Simultaneous equations: one linear, one quadraticElimination by adding or subtracting equations does not work when one equation has squared terms.
21.1Equations quadratic in a function of xLook for two terms where one power is exactly double the other, plus a constant.
2Assessment pointTopic question bank, 40 multiple-choice questions: print or review, or assign in the app for a marked score.
Examiner traps to pre-empt:
  • The sign inside the bracket matches the sign of \(b\): \(x^{2} - 6x\) gives \((x - 3)^{2}\), not \((x + 3)^{2}\).
  • Writing \(2x^{2} - 12x + 7 = 2(x - 3)^{2} - 9 + 7\) is the classic slip: the 9 sits INSIDE the bracket that is multiplied by 2, so it must become 18.
  • The vertex of \(a(x + p)^{2} + q\) is at \(x = -p\), not \(x = p\): \((x + 1)^{2}\) is zero when \(x = -1\).

1.2Functions

Weeks 2 to 3
WeekRefLessonLearning intention
21.2Functions: domain, range and compositionIn the lab, choose a function and follow the mapping diagram as each input in the domain is sent to its output: the set of outputs is the range.
31.2Inverse functionsIn the lab, pick a function and watch its inverse appear as the reflection in \(y = x\): every point \((a, b)\) on \(y = f(x)\) becomes \((b, a)\).
31.2Transformations of graphsA translation slides the whole graph without changing its shape.
3Assessment pointTopic question bank, 24 multiple-choice questions: print or review, or assign in the app for a marked score.
Examiner traps to pre-empt:
  • Do not just substitute the two ends of the domain.
  • The least \(k\) is the \(x\)-coordinate of the vertex, not its \(y\)-coordinate.
  • \(fg(x)\) is NOT \(f(x) \times g(x)\).

1.3Coordinate geometry

Weeks 3 to 4
WeekRefLessonLearning intention
31.3Equations of straight linesIn the lab, drag the two points and watch the gradient and the equation of the line update as you go.
41.3The equation of a circleA point \((x, y)\) is on the circle when its distance from the centre \((a, b)\) is \(r\).
41.3Intersections of lines and curvesIn the lab, draw a curve and a line and read off where they cross: those \(x\)-values are exactly the solutions of the equation formed by setting the two expressions equal.
4Assessment pointTopic question bank, 24 multiple-choice questions: print or review, or assign in the app for a marked score.
Examiner traps to pre-empt:
  • The gradient of \(3x + 4y = 24\) is not 3 (nor \(\frac{4}{3}\)).
  • The perpendicular gradient is the NEGATIVE reciprocal.
  • In the length formula, subtract the coordinates before squaring: from \((-1, 3)\) to \((5, -5)\) the changes are 6 and \(-8\), giving \(\sqrt{36 + 64} = 10\).

1.4Circular measure

Weeks 4 to 5
WeekRefLessonLearning intention
41.4RadiansImagine bending a piece of string the length of the radius around the edge of a circle.
51.4Arc length and sector areaA sector with angle \(\theta\) is the fraction \(\dfrac{\theta}{2\pi}\) of the whole circle, so its arc is \(\dfrac{\theta}{2\pi} \times 2\pi r = r\theta\).
5Assessment pointTopic question bank, 16 multiple-choice questions: print or review, or assign in the app for a marked score.
Examiner traps to pre-empt:
  • Your calculator must be in the right mode. \(\sin 1.2\) in degree mode gives \(0.0209\) instead of \(0.932\).
  • Do not multiply \(\dfrac{7\pi}{12}\) by 180 and stop: that gives \(105\pi\), not \(105^\circ\).
  • Never mix units in an angle sum.

1.5Trigonometry

Weeks 5 to 6
WeekRefLessonLearning intention
51.5Graphs of trigonometric functionsIn the lab, drag the point round the unit circle and watch its height trace out the sine graph and its across-distance trace out the cosine graph.
51.5Exact values and the two identitiesIn the lab, step the angle through \(30^\circ\), \(45^\circ\) and \(60^\circ\) and compare the exact values it shows with the sides of the triangles in Fig. 1.
61.5Solving trigonometric equationsIn the lab, move the horizontal line \(y = k\) and watch where it cuts the curve.
6Assessment pointTopic question bank, 24 multiple-choice questions: print or review, or assign in the app for a marked score.
Examiner traps to pre-empt:
  • The tangent graph repeats every \(\pi\), not every \(2\pi\), and it has no maximum or minimum.
  • \(y = \sin(x + k)\) moves the graph LEFT by \(k\), not right; and in \(y = \sin 2x\) the period halves, it does not double.
  • Watch the ends of the interval.

1.6Series

Weeks 6 to 7
WeekRefLessonLearning intention
61.6The binomial expansionMultiply out \((a + b)^2\), \((a + b)^3\), \((a + b)^4\) and the coefficients build Pascal's triangle (Fig. 1).
61.6Arithmetic progressionsIn the lab, set the first term and the common difference with the sliders and watch each term grow by the same step.
71.6Geometric progressions and sum to infinityIn the lab, choose a first term and a multiplier and watch the terms.
7Assessment pointTopic question bank, 24 multiple-choice questions: print or review, or assign in the app for a marked score.
Examiner traps to pre-empt:
  • \(\binom{5}{2}\) is not \(\dfrac{5!}{2!} = 60\).
  • Bracket the whole second term before squaring: \((-3x)^2 = 9x^2\), not \(-3x^2\) and not \(-9x^2\).
  • The \(x^3\) term is the FOURTH term (\(r = 3\)), because counting starts at \(r = 0\).

1.7Differentiation

Weeks 7 to 8
WeekRefLessonLearning intention
71.7The gradient of a curveIn the lab, fix a point on the curve and drag the second point of the chord towards it.
71.7Differentiating powers and the chain ruleThe rule \(\dfrac{d}{dx}x^{n} = nx^{n-1}\) works for every rational \(n\): negative, fractional, the lot.
81.7Tangents, normals and rates of changeThree steps every time: find the point (both coordinates), find the gradient by substituting into \(\dfrac{dy}{dx}\), then use \(y - y_{1} = m(x - x_{1})\).
81.7Stationary points and their natureIn the lab, slide the point along the curve and watch the tangent.
8Assessment pointTopic question bank, 32 multiple-choice questions: print or review, or assign in the app for a marked score.
Examiner traps to pre-empt:
  • Do not put \(h = 0\) into \(\dfrac{12h + 6h^{2} + h^{3}}{h}\) straight away: that gives \(\dfrac{0}{0}\), which means nothing.
  • \(\dfrac{d^{2}y}{dx^{2}}\) is NOT \(\left(\dfrac{dy}{dx}\right)^{2}\).
  • After solving \(\dfrac{dy}{dx} = 0\) for \(x\), substitute into the equation of the CURVE to get \(y\).

1.8Integration

Weeks 8 to 9
WeekRefLessonLearning intention
81.8Integration as reverse differentiationDifferentiating takes the power down and reduces it by one.
91.8Definite integrals and areaIntegrate as usual, write the result in square brackets with the limits, then substitute the top limit and subtract the value at the bottom limit.
91.8Volumes of revolutionRotate the region under \(y = f(x)\) through \(360^{\circ}\) about the \(x\)-axis.
9Assessment pointTopic question bank, 24 multiple-choice questions: print or review, or assign in the app for a marked score.
Examiner traps to pre-empt:
  • Dividing by a fraction is multiplying by its reciprocal: \(\dfrac{x^{\frac{3}{2}}}{\frac{3}{2}} = \tfrac{2}{3}x^{\frac{3}{2}}\), not \(\tfrac{3}{2}x^{\frac{3}{2}}\).
  • Divide by \(a\); do not multiply. \(\displaystyle\int (2x + 1)^{3}\,dx\) is \(\dfrac{(2x + 1)^{4}}{8}\), not \(\dfrac{2(2x + 1)^{4}}{4}\).
  • Find \(c\) straight after integrating, using the equation of the CURVE (\(y\)), not the gradient.
Topic 02

Pure Mathematics 2

Weeks 9 to 17

3.1Algebra

Weeks 9 to 10
WeekRefLessonLearning intention
93.1The modulus functionDraw the straight line \(y = ax + b\) first, then reflect every part that lies below the \(x\)-axis in the \(x\)-axis.
103.1Polynomial division, factor and remainder theoremsPolynomial division works like numerical long division.
103.1Partial fractionsEverything depends on writing down the correct form before you calculate anything.
103.1The binomial series for any rational nFor a positive integer \(n\) the expansion stops after \(n + 1\) terms.
10Assessment pointTopic question bank, 32 multiple-choice questions: print or review, or assign in the app for a marked score.
Examiner traps to pre-empt:
  • The vertex of \(y = |2x - 3|\) is at \(x = 1.5\), not \(x = 3\) or \(x = -1.5\).
  • In Case 2, \(-(2x - 1)\) is \(-2x + 1\), not \(-2x - 1\).
  • Never square when one side might be negative: \(2x + 5 < |x + 1|\) squared gives a wrong answer, because squaring a negative left side flips which side is bigger.

3.2Logarithmic and exponential functions

Weeks 11 to 12
WeekRefLessonLearning intention
113.2Logarithms and the laws of logarithms\(2^5 = 32\) and \(\log_2 32 = 5\) say the same thing: the power of 2 that gives 32 is 5.
113.2The exponential function and natural logarithmsIn the lab, set a positive percentage rate and watch the curve climb faster and faster; then make the rate negative and watch it decay towards zero.
113.2Solving exponential equations and inequalitiesTaking logarithms turns an index equation into an ordinary one, because \(\ln a^{k} = k\ln a\).
123.2Reducing relationships to linear formTake ln of both sides of the model and expand with the laws of logarithms.
12Assessment pointTopic question bank, 32 multiple-choice questions: print or review, or assign in the app for a marked score.
Examiner traps to pre-empt:
  • \(\log_2 \dfrac{1}{8}\) is \(-3\), not \(\dfrac{1}{3}\) or \(-\dfrac{1}{3}\).
  • There is no law for \(\log(x + y)\): \(\log_a(x + y) \ne \log_a x + \log_a y\).
  • Do not 'cancel the logs' term by term: \(\log_2(x + 3) + \log_2(x - 1) = 5\) does NOT give \((x + 3) + (x - 1) = 5\) or \(= 32\).

3.3Trigonometry

Weeks 12 to 13
WeekRefLessonLearning intention
123.3Secant, cosecant and cotangentEach new function is one over an old one.
123.3Compound angle formulaeFig. 1 shows where \(\sin(A + B)\) comes from: the height of P is built from two pieces.
133.3Double angle formulaePut \(B = A\) in each compound angle formula.
133.3Expressing a sin x + b cos x as R sin(x + a)Fig. 1 shows that \(3\sin x + 4\cos x\) is just a sine wave of amplitude 5, shifted left.
13Assessment pointTopic question bank, 32 multiple-choice questions: print or review, or assign in the app for a marked score.
Examiner traps to pre-empt:
  • \(\sec x\) is NOT \(\cos^{-1} x\).
  • The identity is \(\sec^2\theta = 1 + \tan^2\theta\), not \(\sec^2\theta = 1 - \tan^2\theta\) or \(\tan^2\theta = 1 + \sec^2\theta\).
  • Never work on both sides at once, and never cross-multiply an identity you are asked to prove: that assumes the result.

3.4Differentiation

Weeks 13 to 14
WeekRefLessonLearning intention
133.4Derivatives of exponentials, logarithms and trigonometric functions\(e^{x}\) is the one function that is its own derivative.
143.4The product and quotient rulesName the two factors \(u\) and \(v\), differentiate each (chain rule if needed), then combine: first times derivative of second, plus second times derivative of first.
143.4Parametric and implicit differentiationWhen \(x\) and \(y\) both depend on a parameter \(t\), differentiate each with respect to \(t\) and divide.
14Assessment pointTopic question bank, 24 multiple-choice questions: print or review, or assign in the app for a marked score.
Examiner traps to pre-empt:
  • \(\dfrac{d}{dx}\ln(4x) = \dfrac{4}{4x} = \dfrac{1}{x}\), NOT \(\dfrac{4}{x}\) and not \(\dfrac{1}{4x}\).
  • The minus sign belongs to cosine: \(\dfrac{d}{dx}\cos x = -\sin x\), but \(\dfrac{d}{dx}\sin x = +\cos x\).
  • \(\tan^{-1} x\) is the inverse function, not \(\dfrac{1}{\tan x} = \cot x\).

3.5Integration

Weeks 14 to 16
WeekRefLessonLearning intention
143.5Integrating exponentials, 1/(ax + b) and trigonometric functionsEach result below is a derivative read backwards.
153.5Integration using trigonometric identitiesRearrange \(\cos 2x = 1 - 2\sin^2 x = 2\cos^2 x - 1\) to express each square in terms of \(\cos 2x\).
153.5Integration using partial fractions and f'(x)/f(x)Differentiate \(\ln|f(x)|\) with the chain rule and you get \(\dfrac{f'(x)}{f(x)}\).
153.5Integration by substitutionTreat \(\dfrac{du}{dx}\) like a fraction to swap \(dx\) for \(du\).
163.5Integration by partsIntegrate the product rule \(\dfrac{d}{dx}(uv) = u\dfrac{dv}{dx} + v\dfrac{du}{dx}\) and rearrange to get the formula.
163.5The trapezium ruleSplit \([a, b]\) into \(n\) equal intervals (strips).
16Assessment pointTopic question bank, 48 multiple-choice questions: print or review, or assign in the app for a marked score.
Examiner traps to pre-empt:
  • \(\displaystyle\int \dfrac{1}{2x+1}\,dx\) is NOT \(\ln|2x+1|\).
  • \(\displaystyle\int \sin x\,dx = -\cos x\), with a MINUS.
  • Do not forget the \(\dfrac{1}{a}\) in front of \(\tan^{-1}\), and do not leave \(\tan^{-1}1\) in degrees: \(\tan^{-1}1 = \dfrac{\pi}{4}\), never 45, inside a calculus answer.

3.6Numerical solution of equations

Weeks 16 to 17
WeekRefLessonLearning intention
163.6Locating roots by a change of signIn the lab, choose a curve and move the line across it.
173.6Iterative methodsAn iterative formula \(x_{n+1} = F(x_n)\) builds a sequence \(x_1, x_2, x_3, \ldots\): each term is \(F\) of the one before.
17Assessment pointTopic question bank, 16 multiple-choice questions: print or review, or assign in the app for a marked score.
Examiner traps to pre-empt:
  • In a sketch-and-count question the marks are for two correct graph shapes in the right places AND a stated conclusion ("one point of intersection, so one root").
  • Compare with zero, not with each other: you must rearrange to \(f(x) = 0\) first.
  • No sign change does NOT mean no root. \(f(x) = (x-1)^2\) has a root at \(x = 1\) but is positive on both sides; and two roots between \(a\) and \(b\) cancel out the sign change.
Topic 03

Pure Mathematics 3

Weeks 17 to 20

3.7Vectors

Weeks 17 to 18
WeekRefLessonLearning intention
173.7Vectors in two and three dimensionsIn the lab, build a vector from its components and watch its length update: the length is Pythagoras on the components.
173.7The vector equation of a lineRead \(\mathbf{r} = \mathbf{a} + t\mathbf{b}\) as a set of directions: from the origin go to \(A\), then walk \(t\) lots of \(\mathbf{b}\).
183.7Parallel, intersecting and skew linesPicture the edges of a box (Fig. 1).
183.7The scalar productThe scalar (dot) product has two forms.
18Assessment pointTopic question bank, 32 multiple-choice questions: print or review, or assign in the app for a marked score.
Examiner traps to pre-empt:
  • \(\overrightarrow{AB}\) is \(\mathbf{b} - \mathbf{a}\), not \(\mathbf{a} - \mathbf{b}\).
  • Parallel vectors need ONE common factor for every component. \((2, 4, 6)\) and \((1, 2, 4)\) look alike, but the factors are \(2, 2, 1.5\), so they are not parallel.
  • The midpoint is half the SUM of the position vectors, \(\tfrac{1}{2}(\mathbf{a} + \mathbf{b})\).

3.8Differential equations

Weeks 18 to 19
WeekRefLessonLearning intention
183.8Forming differential equationsEvery modelling statement has the same three parts: WHICH quantity changes (the top of the derivative), with respect to WHAT (usually time \(t\)), and what the rate depends on.
193.8Solving by separating the variablesTreat \(\dfrac{dy}{dx}\) as if it were a fraction: divide by the \(y\)-part and 'multiply' by \(dx\), so that each side has only one variable.
19Assessment pointTopic question bank, 16 multiple-choice questions: print or review, or assign in the app for a marked score.
Examiner traps to pre-empt:
  • 'Rate of change' with no other words means with respect to TIME.
  • If you write \(\dfrac{dh}{dt} = -k\sqrt{h}\), then \(k\) must come out POSITIVE.
  • 'Growing fastest' means the RATE \(\dfrac{dN}{dt}\) is a maximum.

3.9Complex numbers

Weeks 19 to 20
WeekRefLessonLearning intention
193.9Complex numbers: arithmetic in Cartesian formNo real number squares to \(-1\), so we invent one: \(i = \sqrt{-1}\).
193.9The Argand diagram, modulus-argument and exponential formOn an Argand diagram the real part goes across and the imaginary part goes up.
203.9Complex roots and square rootsTake the conjugate of a whole polynomial equation with real coefficients: the coefficients do not change, but every \(z\) becomes \(z^{*}\).
203.9Loci in the Argand diagramRewrite every modulus in the form \(|z - a|\), so you can read off the centre \(a\).
20Assessment pointTopic question bank, 32 multiple-choice questions: print or review, or assign in the app for a marked score.
Examiner traps to pre-empt:
  • \(\sqrt{-36}\) is \(6i\), not \(-6\) or \(6\).
  • \(zz^{*} = x^{2} + y^{2}\), always real and never negative.
  • You cannot divide parts separately: \(\dfrac{3 + 4i}{1 - 2i}\) is NOT \(3 - 2i\).
Topic 04

Mechanics

Weeks 20 to 24

4.1Forces and equilibrium

Weeks 20 to 21
WeekRefLessonLearning intention
204.1Forces, components and resultantsBefore any calculation, draw a force diagram: the particle as a dot, every force as an arrow starting from it, each labelled.
214.1Equilibrium of a particleIn the lab, set the hanging weight to 40 N and the string angles to \(30^\circ\) and \(50^\circ\).
214.1Friction and limiting equilibriumWhen two rough surfaces touch, the contact force has a component perpendicular to the surface (the normal reaction \(R\)) and a component along it (friction \(F\)).
21Assessment pointTopic question bank, 24 multiple-choice questions: print or review, or assign in the app for a marked score.
Examiner traps to pre-empt:
  • Weight and normal reaction are NOT a third-law pair: they act on the same body and are different kinds of force.
  • Do not learn "horizontal is cos".
  • Keep the signs.

4.2Kinematics of motion in a straight line

Weeks 21 to 22
WeekRefLessonLearning intention
214.2Displacement, velocity and acceleration graphsIn the lab, give the particle a positive initial velocity and a negative acceleration, and run it for long enough that it turns round.
224.2Constant acceleration: the suvat equationsIn the lab, release the ball from a chosen height and step through the strobe images.
224.2Variable acceleration: using calculusGiven displacement as a function of time, differentiate once for velocity and again for acceleration. "At rest" (or "instantaneously at rest") means \(v = 0\); "maximum velocity" usually means \(a = 0\).
22Assessment pointTopic question bank, 24 multiple-choice questions: print or review, or assign in the app for a marked score.
Examiner traps to pre-empt:
  • Average speed is total DISTANCE divided by time, not the average of the start and end speeds (that only works for constant acceleration).
  • On a displacement-time graph the HEIGHT is position, not speed.
  • Area below the time axis is negative DISPLACEMENT but positive DISTANCE.

4.3Momentum

Week 22
WeekRefLessonLearning intention
224.3Momentum and the conservation of momentumIn the lab, give A and B velocities in opposite directions and watch the total momentum readout before and after the collision.
22Assessment pointTopic question bank, 8 multiple-choice questions: print or review, or assign in the app for a marked score.
Examiner traps to pre-empt:
  • Subtracting the speeds gives \(0.2(15 - 12) = 0.6\) N s, which is wrong.
  • Every unknown velocity after the collision should be written as a signed variable, and the sign of the answer tells you the direction.
  • Do not do both collisions in one equation unless all the particles really do end up moving together.

4.4Newton's laws of motion

Week 23
WeekRefLessonLearning intention
234.4Newton's laws of motionIn the lab, set the friction coefficient to zero and double the applied force: the acceleration doubles.
234.4Motion on an inclined planeOn a smooth plane the only force along the slope is the weight component \(mg\sin\alpha\), so \(a = g\sin\alpha\) down the plane whichever way the particle is moving.
234.4Connected particles and pulleysFor a car towing a trailer in a straight line, you can write \(F = ma\) for the car, for the trailer, or for the whole system.
23Assessment pointTopic question bank, 24 multiple-choice questions: print or review, or assign in the app for a marked score.
Examiner traps to pre-empt:
  • \(F = ma\) uses the RESULTANT force.
  • Keep signs consistent.
  • "Moving upwards" does not mean "accelerating upwards".

4.5Energy, work and power

Week 24
WeekRefLessonLearning intention
244.5Work done by a forceIn the lab, keep the pulling force fixed and raise the angle of the rope from \(0^\circ\) towards \(90^\circ\).
244.5Kinetic and potential energy, the work-energy principleIn the lab, release the ball on the slope with friction set to zero and watch the bar chart: potential energy drains into kinetic energy and the total bar stays the same height.
244.5Power and driving forceIn the lab, set the road slope to zero, start the car and watch the speed-time graph level off.
24Assessment pointTopic question bank, 24 multiple-choice questions: print or review, or assign in the app for a marked score.
Examiner traps to pre-empt:
  • Do not use the full force when it is at an angle: \(60 \times 8 = 480\) J is the work only if the rope is horizontal.
  • Work done by the weight on a slope uses the VERTICAL height, \(mg \times d\sin\alpha\), not \(mg \times d\).
  • With the rope at an angle, the normal reaction is NOT \(mg\).
Topic 05

Probability & Statistics 1

Weeks 25 to 28

5.1Representation of data

Week 25
WeekRefLessonLearning intention
255.1Stem-and-leaf, box plots, histograms and cumulative frequencyOpen the histogram tab of the lab and widen one class.
255.1Measures of central tendency and variationIn the frequency-table tab of the lab, change one frequency and watch which averages move.
255.1Variance and standard deviation, including coded dataEach value's deviation is \(x - \bar{x}\).
25Assessment pointTopic question bank, 24 multiple-choice questions: print or review, or assign in the app for a marked score.
Examiner traps to pre-empt:
  • Plotting frequency (not frequency density) on the vertical axis when the class widths differ.
  • Forgetting to reverse the left-hand leaves.
  • Plotting cumulative frequencies at the class midpoints.

5.2Permutations and combinations

Week 26
WeekRefLessonLearning intention
265.2Permutations: arrangements in a line and with restrictionsFill the places one at a time: \(n\) choices for the first place, \(n - 1\) for the next, and so on, giving \(n! = n(n-1)\cdots 2 \times 1\).
265.2Combinations: selectionsChoosing Ali, Ben and Cy is the same selection as choosing Cy, Ali and Ben.
26Assessment pointTopic question bank, 16 multiple-choice questions: print or review, or assign in the app for a marked score.
Examiner traps to pre-empt:
  • Dividing by \(3! + 2!\) instead of \(3! \times 2!\).
  • Forgetting the internal arrangements of the block.
  • Using 'total minus together' for three or more people who must all be apart.

5.3Probability

Weeks 26 to 27
WeekRefLessonLearning intention
265.3Probability: sample spaces, exclusive events and tree diagramsIn the lab's sample-space tab, roll two dice many times and compare the frequency of each total with the grid of 36 outcomes.
275.3Conditional probability and independenceIn the lab's conditional tab, click on a condition and watch the sample space shrink to just those outcomes.
27Assessment pointTopic question bank, 16 multiple-choice questions: print or review, or assign in the app for a marked score.
Examiner traps to pre-empt:
  • Saying P(total 8) \(= \dfrac{1}{11}\) because there are 11 possible totals.
  • Adding probabilities of events that are NOT exclusive.
  • Keeping the same denominators on the second branches.

5.4Discrete random variables

Weeks 27 to 28
WeekRefLessonLearning intention
275.4Discrete probability distributions, E(X) and Var(X)A probability distribution lists every value a discrete random variable \(X\) can take, with its probability.
275.4The binomial distributionCheck the four conditions every time, and say them in the context of the question when asked to justify the model.
285.4The geometric distributionThe conditions are the same as for the binomial (independent trials, two outcomes, constant \(p\)) except that there is NO fixed number of trials: you stop at the first success.
28Assessment pointTopic question bank, 24 multiple-choice questions: print or review, or assign in the app for a marked score.
Examiner traps to pre-empt:
  • Forgetting that \(\text{P}(X \ge 3)\) includes 3. 'At least 3' and 'more than 2' are the same event for whole-number values; 'more than 3' is not.
  • Missing a route in \(\text{P}(X = 1)\).
  • Stopping at \(\text{E}(X^2)\), or writing \(\text{Var}(X) = \text{E}(X^2) - \text{E}(X)\).

5.5The normal distribution

Week 28
WeekRefLessonLearning intention
285.5The normal distributionA normal distribution is fixed by its mean \(\mu\) and variance \(\sigma^2\), written \(\text{N}(\mu, \sigma^2)\).
285.5The normal approximation to the binomialA binomial distribution is roughly bell-shaped when \(n\) is large and \(p\) is not too close to 0 or 1.
28Assessment pointTopic question bank, 16 multiple-choice questions: print or review, or assign in the app for a marked score.
Examiner traps to pre-empt:
  • Dividing by the variance. \(\text{N}(50, 16)\) means \(\sigma^2 = 16\), so \(\sigma = 4\); \(\dfrac{56 - 50}{16}\) is wrong.
  • Writing \(\Phi(0.75) - \Phi(1)\) for \(\text{P}(46 < X < 53)\).
  • Using \(z = 0.1\) or \(z = 0.8\) in the equation.
Topic 06

Probability & Statistics 2

Weeks 29 to 31

6.1The Poisson distribution

Week 29
WeekRefLessonLearning intention
296.1The Poisson distributionThe Poisson distribution counts events in a fixed interval of time, length, area or volume.
296.1Approximations: binomial to Poisson, Poisson to normalWhen \(n\) is large and \(p\) is small, successes are rare events scattered among many trials, which is exactly the Poisson picture.
29Assessment pointTopic question bank, 16 multiple-choice questions: print or review, or assign in the app for a marked score.
Examiner traps to pre-empt:
  • Do not just recite "independent and random".
  • "More than 2" means \(X \ge 3\), so it is \(1 - \text{P}(X \le 2)\), not \(1 - \text{P}(X \le 3)\).
  • In a two-stage question, do not add the rates to \(\lambda = 6\) for the week and find \(\text{P}(X = 0)\): that is the probability of no faults all week, a different event.

6.2Linear combinations of random variables

Week 29
WeekRefLessonLearning intention
296.2Linear combinations of random variablesMultiplying by \(a\) stretches the spread by \(|a|\), so the variance is multiplied by \(a^{2}\).
29Assessment pointTopic question bank, 8 multiple-choice questions: print or review, or assign in the app for a marked score.
Examiner traps to pre-empt:
  • \(\text{Var}(3X - 5)\) is not \(3 \times 4 - 5\), and not \(3 \times 4\).
  • The commonest Paper 6 error: \(\text{Var}(A - B) = 9 - 16\).
  • Before adding Poisson parameters, put them on the same interval.

6.3Continuous random variables

Week 30
WeekRefLessonLearning intention
306.3Probability density functions, mean and varianceFor a continuous variable, \(f(x)\) is not a probability: it is a height, and probabilities are areas under it.
30Assessment pointTopic question bank, 8 multiple-choice questions: print or review, or assign in the app for a marked score.
Examiner traps to pre-empt:
  • \(f(2) = \tfrac{3}{8}\) is not \(\text{P}(X = 2)\).
  • \(\text{Var}(X) = \int x^{2} f(x)\,dx\) is NOT the variance until you subtract \(\mu^{2}\).
  • The median is not half-way along the domain.

6.4Sampling and estimation

Week 30
WeekRefLessonLearning intention
306.4Populations, samples and the distribution of the sample meanThe population is every item of interest; a sample is the part you actually observe.
306.4Unbiased estimates and confidence intervalsAn estimate is unbiased if, although it varies from sample to sample, it is right on average.
30Assessment pointTopic question bank, 16 multiple-choice questions: print or review, or assign in the app for a marked score.
Examiner traps to pre-empt:
  • "It is too small" or "it is not random" alone rarely scores.
  • \(\text{Var}(\bar{X}) = \dfrac{\sigma^{2}}{n}\), so the standard deviation is \(\dfrac{\sigma}{\sqrt{n}}\), not \(\dfrac{\sigma}{n}\).
  • Use the CLT only when the population is NOT normal and \(n\) is large, and say so.

6.5Hypothesis tests

Week 31
WeekRefLessonLearning intention
316.5Hypothesis tests with binomial and Poisson distributionsEvery test follows the same script.
316.5Hypothesis tests for a population meanUse this when the population is normal (or the sample is large) and \(\sigma\) is given.
316.5Type I and Type II errorsEvery decision could be wrong.
31Assessment pointTopic question bank, 24 multiple-choice questions: print or review, or assign in the app for a marked score.
Examiner traps to pre-empt:
  • Compare the TAIL probability \(\text{P}(X \ge 9)\) with 5%, never the single probability \(\text{P}(X = 9)\).
  • Write hypotheses about the PARAMETER (\(p\) or \(\lambda\)), not about the observed count, and scale \(\lambda\) to the period of the observation: 2 months at 3.2 per month means \(H_0: \lambda = 6.4\).
  • The continuity correction points AWAY from the tail: \(X \ge 95\) becomes \(Y > 94.5\), and \(X \le 8\) becomes \(Y < 8.5\).
Also for this course

Beyond the scheme

Original work by the TheLucidSTEM team. Week numbers assume 3 lessons a week unless you change the control; the download carries the numbers shown.