Question 5 of 8 Step 1 of 1 07:40:22 An engineer has designed a valve that will

Question

Question 5 of 8 Step 1 of 1 07:40:22 An engineer has designed a valve that will regulate water pressure on an automobile engine. The valve was tested on 180 engines and the mean pressure was 6.0 pounds/square inch (psi). Assume the population variance is 0.81. The engineer designed the valve such that it would produce a mean pressure of 6.2 psi. It is believed that the valve does not perform to the specifications. A level of significance of 0.05 will be used. Find the value of the test statistic. Round your answer to two decimal places. Keypad | Answer(How to Enter) 2 Points 017 Hawkes Learning

Explanation / Answer

Given that,
population mean(u)=6.2
standard deviation, =0.9
sample mean, x =6
number (n)=180
null, Ho: =6.2
alternate, H1: !=6.2
level of significance, = 0.05
from standard normal table, two tailed z /2 =1.96
since our test is two-tailed
reject Ho, if zo < -1.96 OR if zo > 1.96
we use test statistic (z) = x-u/(s.d/sqrt(n))
zo = 6-6.2/(0.9/sqrt(180)
zo = -2.98

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