An investment of d dollars at k percent simple annual interest yields $400 over a 2 year period. In terms of d, what dollar amount invested at the same rate will yield $1,600 over a 5 year period?  Choose the most appropriate option.
A) (2d)/3 B) (3d)/4 C) (4d)/3 D) (3d)/2 E) (8d)/5
400 dollars in 2 years means 200 dollars in 1 year.   To get 1600 dollars' it will take 8 years.   To get 1600 in 5 years, we need 8/5 times money. Answer is (8d)/5.
<result>E</result>
An investment of d dollars at k percent simple annual interest yields $400 over a 2 year period. In terms of d, what dollar amount invested at the same rate will yield $1,600 over a 5 year period?