Answer:
Hence the probability that the mean of their utility bills will be less than $75 = P(X < 75) is 0.9736.
Step-by-step explanation:
Now,
Population mean electric bill, [tex]\mu =[/tex] $72
Population standard deviation, [tex]\sigma =[/tex] $6
Standard error of the mean[tex]= \sigma / \sqrt{n} = 6 / \sqrt{15} = 1.5492[/tex]
The probability that the mean of their utility bills will be less than $75 = P(X < 75)
= P[Z < (75 - 72) / 1.5492]
= P[Z < 1.9365]
= 0.9736 (Using Z table)
