Answer:
$100 * (1 + 6.8%/12)^216 + $100*(1+6.8%/12)^215 + ... + $100*(1+6.8%/12)^1
Now note that
x + x^2 + x^3 + ... + x^N = x ( 1 + x + ... + x^(N-1) )
= x ( (x^N -1)/(x-1) )
Here, x = 1+6.8%1 = 1.00566666 and N = 216, so
$100 * ( 1.00566666 ( 1.00566666^216 -1) / 0.00566666 )
= $ 42398.33
The total interest earned is $42,398 - $21,600 = $20,798
Step-by-step explanation:
The generic formula used in this compound interest calculator is V = P(1+r/n)^(nt)
V = the future value of the investment
P = the principal investment amount
r = the annual interest rate
n = the number of times that interest is compounded per year
t = the number of years the money is invested for
