Question

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The operation manager at a tire manufacturing company believes that the mean mileage of a tire is 46,619 miles, with a variance of 8,145,316 . What is the probability that the sample mean would be less than 46,742 miles in a sample of 88 tires if the manager is correct? Round your answer to four decimal places.

Answer 1

Solution :

Given that ,

mean = = 46619

variance = 8145316

standard deviation = = 2854

n = 88

= 46619

= / n = 2854 / 88

P( < 46742) = P(( - ) / < (46742 - 46619) / 2854 / 88 )

= P(z < 0.40)

= 0.6554

  Probability = 0.6554