Inputting variables

Question

a runner's heart rate in beats per minute is given by the formula Heart rate = 65 + 53 / (4t + 1) where t is the number of minutes after the start of a cool-down period. Find the runner's heart rate in 10 minutes. When is the runner's heart rate equal to 68 beats per minute?

Answer 1

For this problem you just plug in the number for the variable.

Heart Rate = 65 + 53/(4t + 1)

Heart Rate = 65 + 53/(4*10 + 1)

Heart Rate = 65 + 53/41

Heart Rate = 66.29

 

If we know heart rate is 68 we can state that

68 = 65 + 53/(4t + 1)

solve for t

3 = 53/(4t + 1)

3(4t+1)=53

12t + 3 = 53

12t = 53

t = 4.16 minutes