Answer: 52 bpm
Step-by-step explanation:
This is our equation so far: (1860/900) - (36/30). We want both denominators (the bottom number in the fraction) to be equal before we subtract.
The running heart rate fraction is 1860/(15 x 60) or 1860/900.
The resting heart rate fraction is 36/30.
We have to multiply 15 by 60 in the running heart rate because there are 60 seconds per minute, and the resting heart rate is measured in seconds, so we want the two denominators to be in the same units of measurement before we do any more work.
We now have to find the number to use for multiplying 36/30 to where they have a common denominator so that we can find the difference (in the same way that you can't subtract 6/12-1/4 but you can subtract 6/12-4/12).
So we divide 900 by 30 to see what number to multiply the resting heart rate by in order to have equal denominators.
900/30=30
Then, we multiply both numbers in the fraction 36/30 by 30 so it will remain proportionately accurate but also have the same denominator as 1860/900.
36 x 30 = 1080
30 x 30 = 900
36/30 is now 1080/900 because we multiplied both numbers by 30. We can now put the fractions in more of a statement.
running heart rate: 1860 beats per 15 minutes
resting heart rate: 1080 beats per 15 minutes
Since heart rate is typically measured as beats per minute, we must divide both fractions by 15 to find the beats per minute.
1860 / 15 = 124
1080 / 15 = 72
To find the difference, we subtract the results.
124 - 72 = 52 beats per minute.
