> GCE Further Mathematics B (MEI) Y432/01: Statistics minor Advanced GCE Mark Scheme for Autumn 2021

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Mark Scheme October 2021 Question Answer Marks AOs Guidance 1 (a) k + 2k + 5k + 10k + 17k = 1 M1 2.4 35k = 1 so 1 k = 35 A1 [2] 1.1 AG 1 (b) The distribution has (strong) negative skew B1 [1] ... 1.1 1 (c) ??(??) = 4 1 7 = 29 7 = 4.143… B1 1.1a BC Accept any equivalent form. Decimal answers should agree to at least 2 significant figures. ??????( ??) = 1 23 245 = 268 245 = 1.094… B1 [2] 1.1 BC Accept any equivalent form. 1 (d) ??(??) = 10 5 7 = 75 7 = 10.714 B1FT 1.1 BC Accept any equivalent form. FT their E(X) from (c) Decimal answers should agree to at least 2 significant figures. ??????( ??) = 27 17 49 = 1340 49 = 27.347 B1FT [2] 1.1 BC Accept any equivalent form. FT their Var(X) from (c)Y432/01 Mark Scheme October 2021 Question Answer Marks AOs Guidance 2 (a) a is the independent variable since the values of a are not subject to random variation B1 [1] 2.4 B1: values of a are controlled B0: d is dependent on a Explanation required 2 (b) d = –1.104a + 197.1 M1 A1 [2] 3.3 1.1 For either –1.104(a) or 197.1 BC y = –1.104x + 197.1 scores M1 A0 2 (c) estimate = 130.9 (m) B1FT [1] 1.1 FT from (b) if the value is plausible from the scatter diagram. Accept 130 as rounded to 2 significant figures. 2 (d) Because this would be extrapolation and it is possible that the relationship is different for young children B1 B1 [2] 2.2b 2.4 For ‘extrapolation’ B1: a 5-year-old child may not be able to read yet B0 for comment about child not being able to drive 2 (e) Residual = 150 – (–1.104… × 40+197.1…) M1 1.1 Subtraction other way around scores M1 only = −3.0 A1FT [2] 1.1 Allow –2.9 (using 1.104 and 197.1) FT from (b) 2 (f) Because the values of a are non-random so it makes no sense to try to predict them. B1 [1] 3.2b Should show understanding of a purpose of a regression line being to make predictions [Show More]

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