Question

About how many years will it take for $4000 to double at a simple interest rate of 9%

Answer 1

Answer:

about 11 years

Step-by-step explanation:

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

$t=?\ years\\ P=\ 4,000\\ A=\ 8,000\\r=9\%=9/100=0.09$

substitute in the formula above

$8,000=4,000(1+0.09t)$

solve for r

$2=(1+0.09t)$

$0.09t=2-1$

$0.09t=1$

$t=11.1\ years$