ACT Math · Exponential and logarithmic functions
A population model is given by P(t) = 500(1.08)^t, where t is measured in years. Which value is closest to P(5)?
A population model is given by , where is measured in years. Which value is closest to ?
Answer and explanation
Answer: H: 735
Substitute into the model: . Since and , we get , so , which is closest to , choice H. Choice F () applies the 8\% growth once, , instead of raising the growth factor to the 5th power. Choice G () uses simple growth, , which ignores compounding. Choice J () is too large; it would need a yearly growth factor close to . Exponential growth compounds each year on the larger amount.
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