statistics
posted by tina .
a study found that the means waiting time to see a physican at an outpatient clinic was 40 minutes with a standard deviation of 28 minutes. use excel to find each probability. a. what is the probability of more than an hours wait? B. less than 20 minutes? C. at least 10 minutes?

I don't know how to use Excel for this.
Z = (score  mean)/SD
See the Help for Excel for Z test.