Question 1077417
The formula for annual compound interest, including principal sum, is:
A = P (1 + r/n) (nt)

Where:

A = the future value of the investment/loan, including interest
P = the principal investment amount (the initial deposit or loan amount)
r = the annual interest rate (decimal)
n = the number of times that interest is compounded per year
t = the number of years the money is invested or borrowed for
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From age 25 to age 50, Jill's futute value is:
{{{ A[1] = 20000*( 1 + .05 )^25 }}}
From age 35 to age 50, Bill's future value is:
{{{ A[2] = 20000*( 1 + .05 )^15 }}}
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{{{ A[1] - A[2] = 20000*( 1 + .05 )^25 - 20000*( 1 + .05 )^15 }}}
{{{ A[1] - A[2] = 20000*( 1.05^25 - 1.05^15 ) }}}
{{{ A[1] - A[2] = 20000*( 3.386355 - 2.078928 ) }}}
{{{ A[1] - A[2] = 20000*1.307427 }}}
{{{ A[1] = A[2] = 26148.54 }}}
Jill has $26,148.54 more than Bill at age 50
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Check my math & get another opinion if you like