Determine unbiased estimates for the mean and variance of the distribution.

In spite of these results the baker insists that his claim is correct.

Stating appropriate hypotheses, test the baker’s claim at the 10 % level of significance.

unbiased estimate of the mean: 795 (grams)     A1

unbiased estimate of the variance: 108 $(gram{s^2})$     (M1)A1

[3 marks]

null hypothesis ${H_0}:\mu  = 800$     A1

alternative hypothesis ${H_1}:\mu  < 800$     A1

using 1-tailed t-test     (M1)

EITHER

p = 0.0812...     A3

OR

with 9 degrees of freedom     (A1)

${t_{calc}} = \frac{{\sqrt {10} (795 - 800)}}{{\sqrt {108} }} = - 1.521$     A1

${t_{crit}} = - 1.383$     A1 

Note: Accept 2sf intermediate results.

THEN

so the baker’s claim is rejected     R1 

Note: Accept “reject ${H_0}$ ” provided ${H_0}$ has been correctly stated.

Note: FT for the final R1.

[7 marks]

A successful question for many candidates. A few candidates did not read the question and adopted a 2-tailed test.

A successful question for many candidates. A few candidates did not read the question and adopted a 2-tailed test.