Question

An investment of $8000 in a certain Certificate of deposit (cd) doubles in value every 7 years. The function that models the growth of this investment is f(x)=8000•2^x, where x is the number of doubling periods. If the investor does not withdraw any money from this cd, how much money will be available for withdrawal after 28 years?

Answer 1

$128,000.

Explanation:

28 years is 4 doubling periods ( 4 * 7).

So the amount of money after 28 years

= 8000* 2^4

= $128,000.

Answer 2

Answer:the available amount after 28 years is $128000

Explanation:

The initial value of the investment is

$8000. The value doubles in every 7 years.

The function that models the growth of this investment is f(x)=8000•2^x

where

x represents the number of doubling periods.

To determine the amount of money that will be available for withdrawal after 28 years, we would determine the number of doubling periods first. Therefore,

x = 28/7 = 4

Therefore, the available amount after 28 years would be

f(x)=8000•2^4 = 8000×16 = $128000