An electrical company claims that the average life of the bulbs it manufactures is 1 300 hours with a standard deviation of 260 hours. If a random sample of 110 bulbs is chosen, what is the...

An electrical company claims that the average life of the bulbs it manufactures is 1 300 hours with a standard deviation of 260 hours. If a random sample of 110 bulbs is chosen, what is the probability that the sample mean will be: a. greater than 1 160 hours? b. less than 1 260 hours? c. between 1 160 and 1 260 hours