Let A's initial investment = 18x and B's initial investment = 7x
For the first 4 months:
A's investment = 18x for 4 months
B's investment = 7x for 4 months
After 4 months, A invested $2000 more and B invested $7000 more each month for the remaining 8 months.
For the next 8 months: A's investment = (18x + 2000) for 8 months B's investment = (7x + 7000) for 8 months
Total investment-time for A = 18x × 4 + (18x + 2000) × 8 = 72x + 144x + 16000 = 216x + 16000
Total investment-time for B = 7x × 4 + (7x + 7000) × 8 = 28x + 56x + 56000 = 84x + 56000
Given that profit is distributed in ratio 2:1, the investment ratio should also be 2:1
So: (216x + 16000)/(84x + 56000) = 2/1
216x + 16000 = 2(84x + 56000)
216x + 16000 = 168x + 112000
216x - 168x = 112000 - 16000
48x = 96000
x = 2000
Therefore:
A's initial investment = 18x = 18 × 2000 = $36000
B's initial investment = 7x = 7 × 2000 = $14000
Total initial investment = $36000 + $14000 = $50000
The answer is A) $50,000