Records on a fleet of trucks reveal that the average life of a set of spark...

Records on a fleet of trucks reveal that the average life of a set of spark plugs is normally distributed with a mean of 22,100 miles. The fleet owner purchased 18 sets and found that the sample average life was 23,400 miles; the sample standard deviation was 1,412 miles. To determine if the spark plugs average 22,100 miles, what is the critical value for the test using a 0.05 level of significance?

A) t = +2.110

B) t ≠ ±2.110

C) t = -2.110

D) t = ±2.110

Solutions

Expert Solution

Sample size =n=18

Degree of freedom =n-1= 18-1 =17

D) t = ±2.110

orchestra answered 1 year ago

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