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Date May 2021 Marks available 2 Reference code 21M.1.SL.TZ2.8
Level Standard Level Paper Paper 1 Time zone Time zone 2
Command term Find Question number 8 Adapted from N/A

Question

At Springfield University, the weights, in kg, of 10 chinchilla rabbits and 10 sable rabbits were recorded. The aim was to find out whether chinchilla rabbits are generally heavier than sable rabbits. The results obtained are summarized in the following table.

A t-test is to be performed at the 5% significance level.

Write down the null and alternative hypotheses.

[2]
a.

Find the p-value for this test.

[2]
b.

Write down the conclusion to the test. Give a reason for your answer.

[2]
c.

Markscheme

(let μc= population mean for chinchilla rabbits, μs= population mean for sable rabbits)

H0:μc=μs           A1

H1:μc>μs          A1


Note:
Accept an equivalent statement in words, must include mean and reference to “population mean” / “mean for all chinchilla rabbits” for the first A1 to be awarded.
         Do not accept an imprecise “the means are equal”.


[2 marks]

a.

p-value =0.0408   0.0408065           A2


Note:
Award A1 for an answer of 0.041565, from “unpooled” settings on GDC.


[2 marks]

b.

0.0408<0.05 .        R1

(there is sufficient evidence to) reject (or not accept) H0                  A1

(there is sufficient evidence to suggest that chinchilla rabbits are heavier than sable rabbits)


Note:
Do not award R0A1. Accept ‘accept H1’.


[2 marks]

c.

Examiners report

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

Syllabus sections

Topic 4—Statistics and probability » SL 4.11—Expected, observed, hypotheses, chi squared, gof, t-test
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Topic 4—Statistics and probability

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