Problema Solution

The cost C, in dollars, to fill a sandbox varies directly as the depth S, in inches, of the sand. The director of Creekside Daycare checks at her local hardware store and finds that it would cost $82.00 to fill the daycare's box with 8 in. of sand. She decides to fill the sandbox to a depth of 10 in. Find and equation of variation.

Answer provided by our tutors

C varies directly to S, the equation to try would be


C=kS


We know that when S = 8 in, C = $82 so,


82=k*8


by solving for k we find:


x = 10.25


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The equation of variation is now C=10.25S


To find C when S= 10 in, simply plug in 10 for S and solve:


C = 10.25*10


C = $102.5