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Date November 2019 Marks available 3 Reference code 19N.2.SL.TZ0.S_1
Level Standard Level Paper Paper 2 Time zone Time zone 0
Command term Write down Question number S_1 Adapted from N/A

Question

The number of messages, M, that six randomly selected teenagers sent during the month of October is shown in the following table. The table also shows the time, T, that they spent talking on their phone during the same month.

The relationship between the variables can be modelled by the regression equation M=aT+b.

Write down the value of a and of b.

[3]
a.

Use your regression equation to predict the number of messages sent by a teenager that spent 154 minutes talking on their phone in October.

[3]
b.

Markscheme

evidence of set up             (M1)

eg      correct value for a or b (accept r=0.966856)

4.30161, 163.330

a=4.30, b=163  (accept y=4.30x+163)        A1A1 N3

[3 marks]

a.

valid approach           (M1)

eg      4.30(154)+163

eg      825.778  (825.2 from 3 sf values)           (A1)

number of messages =826 (must be an integer)         A1  N3

[3 marks]

b.

Examiners report

[N/A]
a.
[N/A]
b.

Syllabus sections

Topic 4—Statistics and probability » SL 4.4—Pearsons, scatter diagrams, eqn of y on x
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Topic 4—Statistics and probability

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