majortests.com

SAT problem solving explanation

Test 11

6. For a wall of a given material and of a fixed surface area, the rate of heat loss by conduction through the wall is inversely proportional to the thickness (T) of the wall, and directly proportional to the temperature difference (d) across the wall. The rate of heat loss could be given by which of the following expressions?

A. 2d/T
B. 2 T/d
C. 2d + ½ T
D. 2(d + ½ T)
E. T/d

Correct Answer: A

Explanation:

Rate (R) is directly proportional to d. We write this as R = k.d, where k is a constant.
Rate is inversely proportional to T. We write this as R = k. 1/T, where k is a constant.
In the combined expression, d must appear in the numerator and T in the denominator. This is the case in A.

Need more help with problem solving questions for the SAT? Try the Kaplan SAT Math Workbook

Next steps

* SAT is a registered trademark of the College Board, which was not involved in the production of, and does not endorse, this product.

All content of site and practice tests copyright © 2014 Study Mode, LLC.