The acidity of human blood is measured on a pH scale and is a normal random variable. The mean pH of blood is 7.2 with a standard deviation of 0.15. Find the probability that random selected person would have a blood pH greater than 7.17.

First find the number of standard deviations:

(7.17-7.2)/.15=-.2

Then use excel to find the percentage of a normal distribution -.2 std dev's below average:

=normsdist(-.2)=.4207

Hope that helps,

Deanna