Problem Solving

If money is invested at r percent interest,compounded annually,the amount of investment will double in approximately 70/r years. If Pat's parents invested $ 5000 in a long term bond that pays 8 percent interest,compounded annually, what will be the approximate total amount of investment 18 years later,when Pat is ready for college?

A)$20000
B)$15000
C)$12000
D)$10000
E)$9000

The money will double in 70/8 = 8.75 year or approximately 9 years

So in 9 years the money will be 10,000. and then it will double again in 9 years that will make it 20,000.


So A