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Deposit for infinite bimonthly withdrawals

Short answer

With 12% nominal annual rate, the two-monthly interest rate is 2%. Capitalized worth = 5000/0.02 = Rs 2,50,000.

How much money should Mr Ram deposit now in a bank so that he and his successor can draw Rs 5000 bimonthly for infinite period? Interest rate is 12% per year.

Assumption: "bimonthly" means once every two months, so there are 6 withdrawals per year. 12% per year is the nominal rate compounded every two months.

 P = ?     withdrawals of 5,000 at months 2, 4, 6, 8, ... forever
  • Interest per two-month period i = 12% / 6 = 2% = 0.02
  • Withdrawal per period A = Rs 5,000
  • For an infinite series, P = A / i (capitalized worth)
  • P = 5,000 / 0.02 = Rs 2,50,000

The deposit is never used up because each period's interest (2% of 2,50,000 = Rs 5,000) is exactly the amount drawn, so the principal stays intact for the successors.

Answer: Rs 2,50,000 should be deposited now.

(If the withdrawal were twice a month, i = 0.5% per half-month and P = 5,000/0.005 = Rs 10,00,000.)

✓ Answer checked by Claude Opus 5.5 (high effort)

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