I deposit $100 every week into a savings account which has 3% interest compunded weekly.
How much money will I have in my account after 7 years?
this is a furure value of an ordinary anuity problem.
I am going to assume it is 3% p.a and that there are 52 weeks in a year.
C=100, i= 0.03/52 n=7*52
Now you can find Future value.