Question the-fu

2.1 Nonlinear Functions - Exponential growth and decay functions
0:00

S of n, equals, 38,000 times a, to the n power

The function S above models the annual salary, in dollars, of an employee n years after starting a job, where a is a constant. If the employee’s salary increases by 4% each year, what is the value of a ?

A.

0.04

B.

0.4

C.

1.04

D.

1.4

The function S above models the annual salary, in dollars, of an employee n years after

Hard-difficulty · SAT Math · Nonlinear Functions — Exponential growth and decay functions. Read the question above, select your answer, and check the full explanation below to understand exactly why the correct choice works.

Answer explanation

Choice C is correct. A model for a quantity S that increases by a certain percentage per time period n is an exponential function in the form S of n equals, we times, open parenthesis, 1 plus r over 100, close parenthesis, to the n power, where I is the initial value at time n equals 0 for r% annual increase. It’s given that the annual increase in an employee’s salary is 4%, so r equals 4. The initial value can be found by substituting 0 for n in the given function, which yields S of 0 equals 38,000. Therefore, we equals 38,000. Substituting these values for r and I into the form of the exponential function S of n equals, we times, open parenthesis, 1 plus r over 100, close parenthesis, to the n power yields S of n equals, 38,000 times, open parenthesis, 1 plus 4 over 100, close parenthesis, to the n power, or S of n equals, 38,000 times, 1 point 0 4 to the n power. Therefore, the value of a in the given function is 1.04.

Choices A, B, and D are incorrect and may result from incorrectly representing the annual increase in the exponential function.