Question

A manufacturer of carpentry screws claims that its production machine is very accurate and that the standard deviation of the length of all screws produced is .08 mm or less. A sample of 30 screws showed a standard deviation of .10. The test statistic to test the manufacturer's claim is _____.

a. 45.31
b. 23.2
c. 18.56
d. 19.2

Answer 1

Option A) 45.31

Explanation:

We are given the following information in the question:

Population standard deviation, σ = 0.08

`\sigma^2 = (0.08)^2 = 0.0064`

Sample size, n = 30

Sample standard deviation, s = 0.10

`s^2 = (0.10)^2 = 0.01`

Test statistic =

`\displaystyle((n-1)s^2)/(\sigma^2) = ((30-1)(0.01))/((0.0064)) = 45.31`

Option A) 45.31