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 a standard deviaiton $1200. The daily revenue totals for the next 30 days will be monitored. What is the probability that the mean daily revenue for the next 30 days will exceed $7500.? (Round answer to four decimal places)

Solution

Normal Distribution
Mean ( u ) =7200
Standard Deviation ( sd )=1200
Number ( n ) = 30
Normal Distribution = Z= X- u / (sd/Sqrt(n) ~ N(0,1)                  
P(X > 7500)         = (7500-7200)/1200/ Sqrt ( 30 )
= 300/219.089= 1.3693
= P ( Z >1.3693) From Standard Normal Table
= 0.0855