Question

Your heart rate rises when you exercise.

During aerobic exercise, your heart rate
should be at least 0.7(220 - a), but no
more than 0.85(220 - a), where a is your
age. Find the target range if you are 14.
years old.

Answer 1

0.7(220-14) -> 0.7(206) = 144.2

0.85(206) = 175.1

So, the target range for a 14yo is 144.2-175.1

Answer 2

The target range is
`144.2 \leq x \leq 175.1`, when you are 14 years old.

Explanation:

We are given the following information in the question:

Lowest range of heart range:

`0.7(220-a)`

Maximum heart range:

`0.85(220-a)`

where a is the age of person.

Let x denote the heart rate of a person.

Then, according to the question:

`0.7(220-a) \leq x \leq 0.85(220-a)`

We have to find a range of heart rate when the age is 14.

Putting a = 14, we have:

`0.7(220-14) \leq x \leq 0.85(220-14)\\144.2 \leq x \leq 175.1`

Hence, the target range is
`144.2 \leq x \leq 175.1`, when you are 14 years old.