Question

If you invest $3,900 at a 7.83% simple annual interest rate, approximately how long will it take for you to have a total of $10,000?
a.
12 years
b.
15 years
c.
20 years
d.
30 years

Answer 1

we know that

The simple interest formula is equal to

$A=P(1+rt)$

where

A is the Final Investment Value

P is the Principal amount of money to be invested

r is the rate of interest  

t is Number of Time Periods

in this problem we have

$t=?\ years\\ P=\ 3,900\\ A=\ 10,000\\r=0.0783$

substitute in the formula above

$10,000=3,900(1+0.0783t)$

Solve for t

$10,000/3,900=(1+0.0783t)$

$(10,000/3,900)-1=0.0783t$

$0.0783t=1.5641$

$t=1.5641/0.0783$

$t=19.98\ years$

therefore

the answer is the option C

$20\ years$

Answer 2

It's c 20 years hope this helps:)