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. what is your friend's heart rate in beats per minute at rest and while running? how many more times does your friend's heart beat in 3 minutes while running than while at rest?

Answer

Part 1:  72 times/minute

Part 2: 150 times/minute

Part 3: 234 times

Explanation

Part 1

18 times in 15 seconds when at rest.

In 1 second = 18/15

                   =  1.2 times/second

In 1 minute = 1.2×60

                  = 72 times/minute

Part 2

25 times in 10 seconds while running.

In 1 second = 25/10

                  = 2.5 times/second

In 1 minute = 2.5×60

                  = 150 times/minute

Part 3

In 3 minutes while at rest = 72×3  = 216

In 3 minutes while running = 150 × 3 = 450

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

Answer = 450 - 216

            = 234 times

b, i believe, but not sure.