Question

Ryan was 8 when his parents invested $4000 in a certificate of deposit that pays 6%. if ryan leaves the account alone until it reaches $10,000, how old will he be? (assume that the interest is not compounded annually.)

Answer 1

Use the simple interest formula which is
I=prt

I interest earned 10000-4000=6000
P principle 4000
R interest rate 0.06
T time?

We need to solve for t
T=I÷pr
T=6,000÷(4,000×0.06)
T=25 years

So Ryan's age is
25 years+8 years=33 years

Answer 33 years