Example

Solving a Direct Variation Application: Calories Burned on a Treadmill

Problem: When Raoul runs on the treadmill at the gym, the number of calories, cc, he burns varies directly with the number of minutes, mm, he uses the treadmill. He burned 315315 calories when he used the treadmill for 1818 minutes.

(a) Write the equation that relates cc and mm.

Step 1. Write the formula for direct variation. y=kxy = kx We will use cc in place of yy and mm in place of xx. c=kmc = km

Step 2. Substitute the given values for the variables. 315=k(18)315 = k(18)

Step 3. Solve for the constant of variation. 31518=k(18)18\frac{315}{18} = \frac{k(18)}{18} 17.5=k17.5 = k

Step 4. Write the equation that relates cc and mm. c=kmc = km Substitute in the constant of variation. c=17.5mc = 17.5m

(b) How many calories would he burn if he ran on the treadmill for 2525 minutes?

Find cc when m=25m = 25. Write the equation that relates cc and mm. c=17.5mc = 17.5m Substitute the given value for mm. c=17.5(25)c = 17.5(25) Simplify. c=437.5c = 437.5

Raoul would burn 437.5437.5 calories if he used the treadmill for 2525 minutes.

0

1

Updated 2026-05-14

Contributors are:

Who are from:

Tags

OpenStax

Elementary Algebra @ OpenStax

Ch.8 Rational Expressions and Equations - Elementary Algebra @ OpenStax

Algebra

Math

Prealgebra

Intermediate Algebra @ OpenStax

Ch.7 Rational Expressions and Functions - Intermediate Algebra @ OpenStax

Related
Learn After