Question

assume that 21 year old womens heart rates at rest are normally distributed with a mean of 74 beats per minute and a standard deviation of 2 beats per minute. if 200 women are examined, how many would you expect to have a heart rate of less than 75?

Answer 1

hopefully you remember the calculator we used last time

if not, here it is

http://www.wolframalpha.com/input/?i=normalcdf&a=*C.normalcdf-_*Formula.dflt-&f2=75&x=6&y=4&f=NormalProbabilities.z_75&f3=74&f=NormalProbabilities.mu_74&f4=2&f=NormalProbabilities.sigma_2&a=*FVarOpt.1-_***NormalProbabilities.z--.***NormalProbabilities.pr--.**NormalProbabilities.l-.*NormalProbabilities.r---.**NormalProbabilities.mu-.*NormalProbabilities.sigma---

Answer 2

the value you want is on line 1, which is 0.6915 (since it's the value for P(Z < 75))

Answer 3

your last step is to multiply that with 200 to get your final answer

Answer 4

138.3?

Answer 5

got the same

Answer 6

so you round that to the nearest integer (because we're talking about a number of people) to get 138