Word Problem: finding pulse rate, given age

[Radar]

When you exercise, your pulse rate rises. Recommended pulse rates vary with age and physical condition. For vigorous exercise, such as jogging,the inequality:

0.7(220-a) <= 0.85(220 -a) gives a target range for pulse rate R (in beats per minute), based on age in years.

A. Substitue your age(55) in the inequality above to find the range for your pulse rate when you are jogging.

B. What is the target range for a person 25 years old?

 

[tkhunny]

We'll be really healthy when you show us how to work all of these.

 

[Radar]

Sorry! This is the first time I've done this and didn't know how it worked.

This is my effort.

a. 0.7(220-a) <= R <= 0.85(220-a)
0.7(220 - 53) <= R <= 0.85(220-53)
0.7(167) <= R <= 0.86(167)
116.9 <= R <= 141.95

b. 0.7(220-a) <= R <= 0.85(220-a)
0.7(220 - 25) <= R <= 0.85(220 - 25)
0.7(195) <= R <= 0.85(195)
136.5 <= R <= 165.75

 

[tkhunny]

No worries, as long as you can take a little ribbing and get on a useful track.

1) I'm a little curious why you used a = 53 when you said a = 55 above, but that's not a problem I can fix. Make up your mind. Also, you have at typo, a 0.86 where you should have used 0.85. However, you managed to use 0.85 in your calculation, so you good.

Looks great.