The owner of a computer repair shop has determined that thei

The owner of a computer repair shop has determined that their daily revenue has mean $7200 and standard deviation $1200. The daily revenue totals for the next 30 days will be monitored. What is the probability that the mean daily revenue of the next 30 days will exceed $7500. (Round your answer or decimal places.) Select the correct answer below.

a. 0.9131

b. 0.0853

c. 0.0869

d. 0.9147

Solution

So the probability is

P(xbar>7500) = P((xbar-mean)/(s/vn) >(7500-7200)/(1200/sqrt(30)))

=P(Z>1.37) =0.0853 (from standard normal table)

Answer: b. 0.0853