### Home > CCA2 > Chapter 10 > Lesson 10.1.1 > Problem 10-12

Aurora is starting a fitness program at her school and needs to find an easy measure of fitness to assign workouts and gauge improvement. She decides that using resting heart rate would be helpful. Assume that the resting heart rate of young women is approximately normally distributed with a mean of 74 beats per minute (bpm) with a standard deviation of 5 bpm. Homework Help ✎

Aurora found a chart that said resting heart rates between 70 and 79 (inclusive) are considered average for women her age. What proportion of her classmates would she expect to find in the average range?

The chart also claims that resting heart rate of 66 or less indicates excellent fitness in otherwise healthy young women. What portion of her classmates would she expect to find in excellent shape?

If Aurora’s fitness program lowers the mean heart rate of her female classmates by 4 bpm, what will be the

*increase*in the proportion of women now classified as being in excellent shape?

normalcdf(70, 79, mean, standard deviation)

normalcdf(-10^99, 66, mean, standard deviation)

What would the new mean be?

Repeat your steps in part (b) with the new mean.