Question

The cost C of printing a magazine is jointly proportional to the number of pages p in the magazine and the number of magazines printed m. (Use k for the constant of proportionality.)

(a) Write an equation that expresses this joint variation.

(b) Find the constant of proportionality if the printing cost is $65,550 for 3800 copies of a 115-page magazine.


(c) How much would the printing cost be for 3500 copies of a 84-page magazine?

Answer 1

a.) C = kpm

b.) 65,550 = k * 115 * 3800 = 437,000k
k = 65,550/437,000 = 0.15

c.) C = 0.15 * 84 * 3500 = $44,100