A Population Is Increasing According to the Exponential Function Defined $y = 3 \mathrm { e }$

Multiple Choice

A population is increasing according to the exponential function defined by $y = 3 \mathrm { e }$ - $04 \mathrm { x }$ , where $\mathrm { y }$ is in millions and $x$ is the number of years. Which of the following should be done in order to answer the question "When will the population reach 4 million?"

A) Solve $3 e ^ { .04 x } = 12$ .
B) Solve $3 e ^ { .04 x } = 4$ .
C) Evaluate $\mathrm { y } = 3 \mathrm { e } ^ { - 04 ( 1 / 4 ) }$ .
D) Evaluate y $= 3 e .04 ( 4 )$ .