Question

Your friend's heart beats 18 times in 15 seconds when at rest. While running, your friend's heart beats 25 times in 10 seconds.

a. Find the heart rate in beats per minute at rest and while running.

While at rest, the heart rate is ?? beats per minute.

While running, the heart rate is ?? beats per minute.

b. How many more times does your friend's heart beat in 3 minutes while running than while at rest? Your friend's heart beats ?? more times while running.

Answer 1

Part A

1. 72 beats per minute

2. 150 beats per minute

Part B

1. 234 more times

Explanation:

Part A:

1.

We can setup a simple ratio to solve for this problem.

Heart beats 18 times in 15 seconds, so heart beats x times in 60 seconds (1 min = 60 sec)

`(18)/(15)=(x)/(60)\\18*60=15x\\1080=15x\\x=(1080)/(15)=72`

At rest, heart rate is 72 beats per minute

Part A:

2.

We can do the same when running.

Heart beats 25 imes in 10 seconds, so heart beats x times in 60 seconds (1 min = 60 sec)

`(25)/(10)=(x)/(60)\\25*60=10x\\1500=10x\\x=(1500)/(10)=150`

While running, the heart rate is 150 beats per minute

Part B:

While running, heart beats 150 times per minute. So in 3 minutes, heart beats 150 * 3 = 450 times

While at rest, heart beats 72 times per minute. So in 3 minutes, heart beats 72 * 3 = 216 times

So the difference is 450 - 216 = 234 times more