Question

The head of maintenance at XYZ Rent-A-Car believes that the mean number of miles between services is 31713171 miles, with a standard deviation of 356356 miles.

If he is correct, what is the probability that the mean of a sample of 4040 cars would be less than 31023102 miles? Round your answer to four decimal places.

Answer 1

Solution :

Given that ,

mean = = 3171

standard deviation = = 356

n = 40

= 3171

= / n = 356 / 40 = 56.2885

P( < 3102) = P(( - ) / < (3102 - 3171) /56.2885 )

= P(z < -1.23)

= 0.1093

probability =0.1093