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In: Statistics and Probability

A car dealer claims that the average wait time for an oil change is less than...

A car dealer claims that the average wait time for an oil change is less than 30 minutes. The population of wait times is normally distributed and 26 customers are sampled. The sample mean is 28.7 minutes and the standard deviation of the sample is 2.5 minutes. Test the claim at the .05 significance level (α=.05) using the traditional method.

Solutions

Expert Solution

Solution :

This is the two tailed test .

The null and alternative hypothesis is ,

H0 :   = 30

Ha : < 30

Test statistic (t)=

= ( - ) / s / n

= (28.7 - 30) / 2.5 / 26

Test statistic = -2.65

P-value = 0.0069

= 0.05

P-value <

Reject the null hypothesis .

There is sufficient evidence to support the claim

orchestra answered 2 years ago
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