Question

An engineer has designed a valve that will regulate water pressure on an automobile engine. The valve was tested on 200 engines and the mean pressure was 7.8 pounds/square inch (psi). Assume the population variance is 1.00. The engineer designed the valve such that it would produce a mean pressure of 7.9 psi. It is believed that the valve does not perform to the specifications. A level of significance of 0.1 will be used. Find the value of the test statistic. Round your answer to two decimal places.

Answer 1

Solution:

Given that,

= 7.9

= 7.8

² = 100

= 10

n = 200

The Test  statistic  z is,

= ( -  ) /  ( /   n)

=( 7.8 - 7.9 ) / (10 / 200 )

= ( - 0.1 *   200 /10 )

= (- 0.1* 200 ) / 10

= - 0.45

Test  statistic   = - 0.45