Question 759440
According to a report by Scarborough Research, the average monthly household cellular phone bill is $73. Suppose local monthly household cell phone bills are normally distributed with a standard deviation of $11.35.

a. What is the probability that a randomly selected monthly cell phone bill is more than $100?
Enter =1-normdist(100,73,11.35,TRUE) on EXCEL, the result is {{{highlight(0.008683)}}}.

b. What is the probability that a randomly selected monthly cell phone bill is between $60 and $83?
Enter =normdist(83,73,11.35,TRUE)-normdist(60,73,11.35,TRUE) on EXCEL, the result is {{{highlight(0.68483)}}}.

c. What is the probability that a randomly selected monthly cell phone bill is between $80 and $90?
Enter =normdist(90,73,11.35,TRUE)-normdist(80,73,11.35,TRUE) on EXCEL, the result is {{{highlight(0.20161)}}}.

d. What is the probability that a randomly selected monthly cell phone bill is no more than $55? 
Enter =normdist(55,73,11.35,TRUE) on EXCEL, the result is {{{highlight(0.056381)}}}