2. The lifetime of light bulb is normally distributed with meanof 1400 hours and standard deviation of 200 hours.
a. What is the probability that a randomly chosen light bulbwill last for more than 1800 hours?
b. What percentage of bulbs last between 1350 and 1550hours?
c. What percentage of bulbs last less than 1.5 standarddeviations below the mean lifetime or longer than 1.5 standarddeviations above the mean?
d. Find a value k such that 20% of the bulbs last longer than khours.
