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

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

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

f ($25) = $42,500
To solve this problem, insert $25 for h and do the math:

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.