Final answer:
To calculate the amount of money in your account at the end of a certain time period with compound interest, use the formula A = P(1+r/n)^(nt), where A is the final amount, P is the principal, r is the annual interest rate, n is the number of times interest is compounded per year, and t is the number of years. Using this formula, at the end of the 21st year, the account balance will be $1,195,540.73 if the interest is compounded daily, $1,195,607.48 if compounded weekly, and $1,195,900.00 if compounded annually.
Step-by-step explanation:
To calculate the amount of money in your account at the end of a certain time period with compound interest, you can use the formula A = P(1+r/n)^(nt), where A is the final amount, P is the principal (initial deposit), r is the annual interest rate (as a decimal), n is the number of times interest is compounded per year, and t is the number of years.
In this case, you are depositing $4600 per month for 7 years, and then stopping payments. Let's calculate how much will be in your account at the end of the 21st year for each scenario:
a) Interest compounded daily: n = 365
A = 4600(1+0.1/365)^(365*7+(21-7)*365) = $1,195,540.73
b) Interest compounded weekly: n = 52
A = 4600(1+0.1/52)^(52*7+(21-7)*52) = $1,195,607.48
c) Interest compounded annually: n = 1
A = 4600(1+0.1/1)^(1*7+(21-7)*1) = $1,195,900.00