Task: Question Answering
Input (English): Problem: if money is invested at r percent interest , compounded annually , the amount of the investment will double in approximately 24 / r years . if pat ' s parents invested $ 6,000 in a long - term bond that pays 8 percent interest , compounded annually , what will be the approximate total amount of the investment 18 years later , when pat is ready for college ? 
Options: a ) $ 20000 , b ) $ 15000 , c ) $ 12000 , d ) $ 10000 , e ) $ 30000
Output (English): e