SOLUTION: A lady stenographer claims that she can take dictation at the rate of 118 words per minute can we reject her claim on the basis of 100 trials in which she demonstrates a mean of 11

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Question 976038: A lady stenographer claims that she can take dictation at the rate of 118 words per minute can we reject her claim on the basis of 100 trials in which she demonstrates a mean of 116 words and a S.D. of 15 words
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
z=%28116-118%29%2F%2815%2Fsqrt%28100%29%29=-1.333
You didn't specify a confidence interval however for the 90% confidence interval, the critical value is 1.645.
So assuming a confidence level of 90% or better, you cannot reject the null hypothesis (mu=118).