GED Math Practice Questions: Evaluating and Solving Functions

If you run into a function problem on the GED Mathematical Reasoning test, you may be asked to either write a function based on a word problem, or to simply plug in values and evaluate the function.

The following practice questions ask you to do both.

Practice questions

  1. Diana’s take-home pay is described by the function f(h) = 2,000h – 0.15 (2,000h). Evaluate f ($25).

  2. A car rental company charges $50 per day plus $0.40 per mile traveled. Write the function that represents the daily cost of the car rental.

Answers and explanations

  1. f ($25) = $42,500

    To solve this problem, insert $25 for h and do the math:


  2. f (m) = $50 + $0.40m

    In this problem, the variable is the number of miles traveled, so use m for miles. The charge is $50/day, so place that to the right of the equal sign, plus 40 cents for every mile traveled, or $0.40 per mile. You then have f (m) = $50 + $0.40m.