Answer:
$33534.73
Step-by-step explanation:
Let the lump sum be P.
The interest, I, on a rate, R%, per annum after T years is given by
[tex]I = PRT/100[/tex]
The amount, A, is
[tex]A = P + I = P(1 + \frac{RT}{100})[/tex]
After 2 years at 4.5% interest rate, the amount is
[tex]A = P(1+\dfrac{4.5\times2}{100}=1.09P[/tex]
$7500 is added after 2 years. The principal for the beginning of the third year is then
1.09P + 7500
The amount after the next 3 years is
[tex]A = (1.09P + 7500)\left(1+\dfrac{4.5\times3}{100}\right)=(1.09P + 7500)\times1.135[/tex]
This is the amount expected to be saved.
[tex]50000=(1.09P + 7500)\times1.135[/tex]
Solving for P, we have
[tex]1.09P + 7500 = 44052.86[/tex]
[tex]1.09P = 36552.86[/tex]
[tex]P = 33534.23[/tex]