The cost C of manufacturing a product can be estimated by the formula C= 0.03 rs t^2, where r and s...

[AAPL]

Official Guide

The cost C of manufacturing a product can be estimated by the formula C= 0.03 rs t^2, where r and s are amounts, in pounds, of two major ingredients and t is production time in hours. if r is increased by 50%, s increased by 20% and t decreased by 30%, by approximately what % will the estimated cost of manufacturing the product change.

A. 40% increase
B. 12% increase
C. 4% increase
D. 12% decrease
E. 24% decrease

OA D

[Scott@TargetTestPrep]

Official Guide

The cost C of manufacturing a product can be estimated by the formula C= 0.03 rs t^2, where r and s are amounts, in pounds, of two major ingredients and t is production time in hours. if r is increased by 50%, s increased by 20% and t decreased by 30%, by approximately what % will the estimated cost of manufacturing the product change.

A. 40% increase
B. 12% increase
C. 4% increase
D. 12% decrease
E. 24% decrease

OA D

Solution:

If we let r = s = t = 10, the original cost would be C = 0.03 x 10 x 10 x 10^2 = $300. Since r is increased by 50%, s increased by 20% and t decreased by 30%, the new cost would be C = 0.03 x 15 x 12 x 7^2 = $264.60. We see this is approximately $36 less than the original $300, or $12 less per every $100, i.e., a 12% decrease.

Answer: D