GED Mathematical Reasoning TestAlgebraic Problem Solving with Graphs and FunctionsEasy
A city planner is analyzing population growth. The population, P, in thousands, can be modeled by the function P(t) = 2t + 50, where t is the number of years since 2000. What was the population in 2015?
- A80 thousand
- B52 thousand
- C90 thousand
- D65 thousand
Show answer & explanationAnswer & explanation
Correct answer: A. 80 thousand
To find the population in 2015, we need to determine the value of t, which is the number of years since 2000. t = 2015 - 2000 = 15. Then, substitute t=15 into the function P(t) = 2t + 50 to calculate the population.
Why the other options are wrong
- B. This would be the population in 2001 (t=1).
- C. This would be the population if t=20, which is incorrect.
- D. This would be the population if t=7.5, which is incorrect.
Evaluating a Function
Evaluating a function means substituting a given value for the input variable (often x or t) into the function's equation and then calculating the resulting output value.
- Input values are typically given as a number or a variable expression.
- Substitute the input value wherever the variable appears in the function.
- Follow the order of operations to simplify the expression and find the output.
Memory trick: Input into the machine, output the result!