Question

The valve was tested on 210 engines and the mean pressure was 5.0 pounds/square inch (psi). Assume the population standard deviation is 0.9. The engineer designed the valve such that it would produce a mean pressure of 4.9 psi. It is believed that the valve does not perform to the specifications. A level of significance of 0.02 will be used. Find the value of the test statistic. Round your answer to two decimal places.

Answer 1

1.6101529

Explanation:

Given the following :

Number of samples (n) = 210

Sample mean (x) = 5

Population standard deviation = 0.9

Population mean (m) = 4.9

Since the standard deviation of the population is known, we can use the z statistic

Z = (x - m) / standard error

Standard error = sd / √n

Standard error = 0.9 / √210

Standard error = 0.9 / 14.491376

Standard error= 0.0621059

Z statistic = (5 - 4.9) / 0.0621059

Z statistic = 0.1 / 0.0621059

Z statistic = 1.6101529