Question

An engineer designed a valve that will regulate water pressure on an automobile engine. The engineer designed the valve such that it would produce a mean pressure of 4.2 pounds/square inch. It is believed that the valve performs above the specifications. The valve was tested on 210 engines and the mean pressure was 4.3 pounds/square Inch. Assume the standard deviation is known to be 0.7. A level of significance of 0.01 will be used. Find the value of the test statistic Round your answer to 2 decimal places Enter the value of the test statistic Answer How to enter your answer m Tables Keypad Keyboard Shortcuts Submit Answer

Answer 1

Sample Size = n = 210

Sample Mean = $\small \overline{x}$ = 4.3

Population Standard deviation = $\small \sigma$ = 0.7

Hypothesised Mean = $\small \mu$ = 4.2

Level of significance = $\small \alpha$ = 0.01

We will use z test statistic given as -

$\small Z=\frac{\sqrt{n}(\overline{x}-\mu)}{\sigma}=\frac{\sqrt{210}(4.3-4.2)}{0.7}=2.07$

Therefore, value of the test statistic = 2.07                 (Answer)