Historically, the average time it takes Jessica to swim the 200 meter butterfly
ID: 3376257 • Letter: H
Question
Historically, the average time it takes Jessica to swim the 200 meter butterfly is 148.4 seconds. Jessica would like to know if her average time has changed. She records her time on 50 randomly selected occasions and computes the mean to be 147.8 seconds with a standard deviation of 2.3 seconds. use alpha = .05
The hypothesis to be tested is:
H0: mu=148.4 vs. Ha: mu not equal 148.4
The test statistic is:
z=-1.845
Please state the correct conclusion.
Reject the null hypothesis.
Fail to reject the null hypothesis.
Not enough information is given.
Accept the null hypothesis.
A.Reject the null hypothesis.
B.Fail to reject the null hypothesis.
C.Not enough information is given.
D.Accept the null hypothesis.
Explanation / Answer
Solution: The correct conclusion is B
B) Fail to reject the null hypothesis.
The |z|=1.845 and z critical value (tabulated value for alpha =0.05) =1.96
The tabulated value is greater than the calculated value.
So, we fail to reject the null hypotheis.
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