Need Help with this compound interest problem!

[anjalipatel727]

If you just save 50 cents a week at the bank doubling your investment every three years, then how much money will you have 25 years from now?If you just save 50 cents a week at the bank doubling your investment every three years, then how much money will you have 25 years from now?

 

[stapel]

If you just save 50 cents a week at the bank doubling your investment every three years, then how much money will you have 25 years from now?If you just save 50 cents a week at the bank doubling your investment every three years, then how much money will you have 25 years from now?

Which are you doing, adding fifty cents each week, or doubling your investment in three years?

What is the exact text of the exercise? (As currently posted, I don't think it makes any sense.) When you reply, please include your efforts so far. Thank you!

 

[HallsofIvy]

Which are you doing, adding fifty cents each week, or doubling your investment in three years?

I would interpret this as both. That is, he is adding fifty cents each week, and earning some compound interest, so that after 3 years, the amount in the account is twice the total amount added, (.50*52*3)= $78. So it must have earned $78 interest

The one piece of information that is missing is how often the interest is compounded. Is it compounded yearly (most common) or monthly (less common) or weekly (very uncommon but would fit with the weekly deposit)?