Example

Calories Burned on a Treadmill: A Direct Variation Application

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 it. He burned 315 calories in 18 minutes.

(a) Find the equation relating cc and mm.

Step 1 — Write the direct variation formula using cc in place of yy and mm in place of xx: c=kmc = km

Step 2 — Substitute the given values (c=315c = 315, m=18m = 18): 315=k18315 = k \cdot 18

Step 3 — Solve for kk: Divide both sides by 1818: k=31518=17.5k = \frac{315}{18} = 17.5

Step 4 — Write the equation: c=17.5mc = 17.5m

(b) Find the calories burned in 25 minutes.

Substitute m=25m = 25 into the equation: c=17.5(25)=437.5c = 17.5(25) = 437.5

Raoul would burn 437.5 calories if he used the treadmill for 25 minutes.

0

1

Updated 2026-04-21

Contributors are:

Who are from:

Tags

OpenStax

Elementary Algebra @ OpenStax

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

Algebra

Math

Prealgebra

Related
Learn After