An Ipsos MediaCT study indicates that mobile device owners who used their mobile device while shopping for consumer ­electronics spent an average of $ 1,539 on consumer electronics in the past six months. (Data extracted from iab.net/ showrooming.) Assume that the amount spent on consumer electronics in the last six months is normally distributed and that the standard deviation is $ 500.

a. What is the probability that a mobile device owner who used his or her mobile device while shopping for consumer electronics spent less than $ 1,000 on consumer electronics?

b. What is the probability that a mobile device owner who used his or her mobile device while shopping for consumer electronics spent between $ 2,500 and $ 3,000 on consumer electronics?

c. Ninety percent of the amounts spent on consumer electronics by mobile device owners who used their mobile device while shopping for consumer electronics are less than what value?

d. Eighty percent of the amounts spent on consumer electronics by mobile device owners who used their mobile device while shopping for consumer electronics are between what two values symmetrically distributed around the mean?