The monthly electrical utility bills of all customers for the far east power and light company are known to be distributed as a normal distribution with mean equal to $87.00 a month and standard deviation of $36.00. if a statistical sample of n = 100 customers is selected at random, what is the probability that the mean bill for those sampled will exceed $75.00?
i honestly believe i'm doing this wrong, i get the formula and plug it all in but its comes out as a what is the answer to this stupid thing?
my work has been (75-87)/36sqrrt(100) and i get -3.33
but the solutions i have to choose from are: :
o -0.33
o approximately 0.63
o about 10
o 3.33