Answer:
money deposited after end of 3rd year is $4877.75 Â
Explanation:
given data
initial amount  = $10000
rate = 5%
time = 3 year
after 7 year account balance = $20000
solution
we consider here money deposited after end of 3rd year is = x
first we get here compounded amount after 3 years as
compounded amount = initial amount × [tex](1+r)^{t}[/tex]   ................1
compounded amount = 10000 × [tex](1+0.05)^{3}[/tex]
compounded amount = $11576.25
so at 7 year account balance is
account balance = ( compounded amount + x )  × [tex](1+r)^{t}[/tex] ....................2
$20000  = ( $11576.25 + x ) × [tex](1+0.5)^{4}[/tex] Â
solve it we get
x = Â $4877.75 Â
so money deposited after end of 3rd year is $4877.75 Â