Answer:
The initial amount, A is approximately $19,991.1.
Step-by-step explanation:
The initial amount the man invests in the bank = A
The amount the man deposits after 15 years = $10,000
The amount in the account after 50 years = $251,894.21
The amount of money after every 15 years = 2 × Initial amount
Therefore, we have;
The amount in the account 15 years after when the man deposits another $10,000 = 2 × A
Therefore the initial amount at the 15th year = 2·A + 10000
The
We have;
2·A = A·(1 + r)¹⁵
(1 + r)¹⁵ = 2
1 + r = 2^(1/15)
r = 1 - 2^(1/15) = 0.04729412282
Therefore, we have;
On the 50th year, 50 - 15 = 35 year
$251,894.21 = (2·A + 10000)·(1 + 0.04729412282)³⁵
A = ($251,894.51/((1 + 0.04729412282)³⁵) - 10000)/2 ≈ $19991.1
The initial amount, A ≈ $19991.1.
