Question

The amount of weight that Sam loses is directly proportional to the number of hours he spends exercising. If Sam loses a pound of weight for each 3 hrs of exercise, how many hours must he spend exercising to lose 25 lbs?
A) 25 hrs
B) 50 hrs
C) 75 hrs
D) 80 hrs

Answer 1

Answer:

The answer is C. 75 hours.

Step-by-step explanation:

In order to determine the hours, we have to know about direct proportionality.

The direct proportionality happens when two variables increase at the same time and their rate is a constant. It means that if one variable is increased, so the other variable will be increased too.

I have attached an image that shows a graph of two variables with direct proportionality.

In this case, we can get the constant of both variables: losing weight and the spending time.

$k=\frac{Weight}{Time}=\frac{1}{3} =0.33$

Then we need to know how many hours Sam will spend to lose 25 lbs:

$\frac{25}{T}=k=0.33\\ T=\frac{25}{0.33}\\ T=75.76$ hours.

Finally, Sam needs to spend 75 hours to lose 25 lbs.

Answer 2

It should be C, 75 hours. To explain why this is, if there is one pound loss for each three hours of exercise, then multiplying you multiply 3 hours of exercise to 75 pounds to get the total number of how many hours is needed to lose 25 pounds.