An electrical firm manufactures a certain type of light bulb that has a mean life of 1800 hours and a standard deviation of 200 hours. Assume the life of these light bulbs follows a normal distribution.
a.Find the probability that a single light bulb will have a life greater than 2000 hours.
b. Find the probability that a random sample of 100 light bulbs will have an average life between 1760 and 1775 hours.