SOLUTION: call was given to the truck. Response time has mean M=8.8 minutes with standard deviation 2.1 minutes. If a random sample of 32 response time is taken, what is the probability that

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Question 870233: call was given to the truck. Response time has mean M=8.8 minutes with standard deviation 2.1 minutes. If a random sample of 32 response time is taken, what is the probability that the average response time is
a) no more than 9 minutes?
b) at least 8 minutes?
c) between 8 and 9 minutes (including 8 and 9 minutes) ?
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!


Hi

Response time has mean M=8.8 minutes with standard deviation 2.1 minutes

random sample of 32 response time is taken:  2.1/sqrt(32) = .3712

a) z = .2/.3712 = .5388, P(z ≤ 9) = 70.50%

b) z = -.8/.3712 = -2.1552, P(z ≥ -2.1552) = 98.44% 

c) P(z ≤ -2.1552) = 1.56%, P(8 ≤ x ≤ 9) = 96.88%