Question

Type the correct answer in the box. Use numerals instead of words. If necessary, use / for the fraction bar. David invested $220 in a savings account that offers a 3% return on the investment. The value of David's investment will be at least $400 after a period of years. Hint: Use the formula A = P(1 + r)t, where A is the amount after t years, P is the amount invested, r is the rate of interest, and t is the time period. Use a calculator to compute the answer, and round it off to the nearest year.

Answer 1

The answer is 23 years.

Explanation:

We will use the formula :

`A=P(1+r)^(t)`

Here P = 220

r = 3%

A = 400

Putting these values in the formula we get,

`400=200(1+0.03)^(t)`

`2=1.03^(t)`

Taking log on both sides,

ln(1.03)t=ln 2

`t=(ln(2))/(ln(1.03))`

t=23.44 or rounding to nearest, t=23 years

The graph of the function can be shown as below.