A company produces steel rods whose lengths follow a normal distribution with mean $μ\mu$ cm and standard deviation $σ\sigma$ cm. A random sample of 16 rods is measured. From this sample, the unbiased estimate of the mean is $xˉ=122.4\bar{x} = 122.4$ and the unbiased estimate of the variance is $s^2 = 3.84$ .

Test, at the 5% level of significance, whether or not $σ\sigma$ is greater than 1.5. State your hypotheses clearly.

Test, at the 5% level of significance, whether or not $μ\mu$ is greater than 121.5.

State an assumption about the distribution of rod lengths that is necessary for these tests to be valid.

Test, at the 5% level of significance, whether or not $σ\sigma$ is greater than 1.5. State your hypotheses clearly.

Test, at the 5% level of significance, whether or not $μ\mu$ is greater than 121.5.

State an assumption about the distribution of rod lengths that is necessary for these tests to be valid.

2.5.3 Hypothesis test for a Normal mean (A-level only)

Question 80

Markscheme

2.5.3 Hypothesis test for a Normal mean (A-level only)

Question 80

Markscheme

2.5.3 Hypothesis test for a Normal mean (A-level only)

Question 80

2.5.3 Hypothesis test for a Normal mean (A-level only) Questions

2.5.3 Hypothesis test for a Normal mean (A-level only)

Question 80

2.5.3 Hypothesis test for a Normal mean (A-level only) Questions