A statistical analysis of 1000 long distance telephone calls made from the headquarters of the Bricks and Clicks Computer Corporation indicates that the length of these calls is normally distributed with u=240 seconds and sigma = 40 seconds.
a. What is the probability that a call lasted less than 180 seconds.
b. What is the probability that a call lasted between 180 and 300 seconds.
c. What is the probability that a call lasted between 110 and 180 seconds.
d. What is the length of a call if only 1% of all calls are shorter.