You contribute $1,000 annually to a retirement account for 8 years and stop making payments at the age of 25. Your twin brother (or sister whichever applies) opens and account at age 25 and contributes $1000 a year until retirement at 65 (40 years). You both earn 10% on your investments. How much can each of you withdraw for 20 years (that is, ages 66 through 85) from the retirement accounts?

To solve this problem, we need to calculate the future value of the retirement accounts for both you and your twin brother/sister.

First, let's calculate the future value of your retirement account. You contribute $1,000 annually for 8 years and earn a 10% return on your investment. We can use the formula for the future value of an ordinary annuity:

FV = P * [(1 + r)^n - 1] / r

Where:
FV = future value
P = payment per period ($1,000)
r = interest rate per period (10% or 0.10)
n = number of periods (8 years)

Plugging in the values:

FV = $1,000 * [(1 + 0.10)^8 - 1] / 0.10

Calculating this, we find that the future value of your retirement account is approximately $14,486.85.

Now, let's calculate the future value of your twin brother/sister's retirement account. They contribute $1,000 annually for 40 years and earn a 10% return on their investment. Using the same formula as before:

FV = $1,000 * [(1 + 0.10)^40 - 1] / 0.10

Calculating this, we find that the future value of your twin's retirement account is approximately $452,592.96.

Finally, to determine how much each of you can withdraw for 20 years (ages 66-85), we need to calculate the annual withdrawals from the retirement accounts. We will assume an annual withdrawal rate of 4% for both accounts.

For your retirement account, the annual withdrawals would be calculated as follows:

Annual Withdrawals = FV * withdrawal rate

Annual Withdrawals = $14,486.85 * 0.04

Calculating this, we find that you can withdraw approximately $579.46 annually for 20 years.

For your twin brother/sister's retirement account, the annual withdrawals would be:

Annual Withdrawals = $452,592.96 * 0.04

Calculating this, we find that your twin can withdraw approximately $18,103.72 annually for 20 years.

So, you can withdraw approximately $579.46 annually, while your twin brother/sister can withdraw approximately $18,103.72 annually during the ages of 66 through 85.