Question

MAKAYLAFO Question 2 of 4 Step 2 of 5 00:54:33 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. The valve was tested on 270 engines and the mean pressure was 43 pounds square inch Assume the variance is known to be 0.49. Is there evidence at the 0.1 level that the valve performs above the specifications? Step 2 of 5: Enter the value of the z test statistic. Round your answer to two decimal places. Answer How to Enter) 2 Points i keypad 2019 Hawkes Learning ere to search

Answer 1

Test statistic = z

= ($\bar x$ - $\mu$ ) / $\sigma$    / $\sqrt$ n

= (4.3 - 4.2) / 0.7 / $\sqrt$ 270

Test statistic = 2.35