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A study of the amount of time it takes a mechanic to rebuild the transmission for a 1992 Chevrolet Cavalier shows that the mean is 8.4 hours and the standard deviation is 1.77 hours. Assume that a random sample of 40 mechanics is selected and the mean rebuild time of the sample is computed. Assuming the rebuilding times are normally distributed, what percentage of sample means are greater than 8.8 hours? Express your answer as a percent rounded to hundredths of a percent.

Respuesta :

Answer:

40.9 %

Step-by-step explanation:

8.8   is   .4 hours above the mean this is  .4/1.77 = .226 standard deviations above the mean

 Using z-score table this corresponds to ~ .5910    (59.10%)

    this percentage is LESS than 8.8 hours

      the percentage ABOVE this is 40.9%

(Not asked, but this is  40.9 (40 ) = ~ 16 of the 40 mechanics sampled)

               

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