I must assume that you know the Compound Interest Formula.
Sally invests some money at 6%/a compounded annually.
After 5 years, she takes the prinicpal and interest and reinvests it all
. . at 7.2%/a compounded quarterly for 6 more years.
At the end of this time, her investment is worth $14784.56.
How much did Sally originally invest?
Let = her original investment.
She earns annual interest for years.
At the end of five years, she will have:. dollars.
She invests this amount at. quarterly for 24 quarters.
At the end of the six years, she will have:. dollars,
. . which, we are told, will equal
There is our equation!. . . . .
Therefore, Sally originally invested