Suppose that pulse rates among healthy adults are normally distributed with a mean of 79 beats/minute and a standard deviation of 10 beats/minute.

Question

Suppose that pulse rates among healthy adults are normally distributed with a mean of 79 beats/minute and a standard deviation of 10 beats/minute. What proportion of healthy adults have pulse rates that are less than 81 beats/minute? Round your answer to at least four decimal places.

Answer 1

z= (81-79/10= 2/10 = 1/5 = 0.2

use a z calculator to find the area under the curve to the left of z=.2

it's slightly more than 50%

to the left of z=0 is exactly 50%

add in the area between z=0 and z=.2

answer: 57.926%= 0.57926

or 0.5793 rounded to 4 decimal places