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IAI Actuarial Core Principles · Actuarial Mathematics for Modelling · Allowing for inflation

A perpetuity pays Rs 50,000 at the end of the first year, and each later annual payment increases in line with inflation of 4% per year. The effective annual interest rate is 9%. What is the present value?

The present value is Rs 1,000,000. For a perpetuity whose first payment is one year away and which grows at a constant rate, the value is the first payment divided by the interest rate minus the growth rate, 50,000 divided by 0.05.

  1. ARs 555,556
  2. BRs 384,615
  3. CRs 1,000,000Correct
  4. DRs 1,090,000
  5. Rs 1,040,000

Explanation

The payments grow at a constant rate g = 4% with the first payment one year away. PV = 50,000/(i - g) = 50,000/0.05 = Rs 1,000,000. Using 50,000/0.09 ignores the growth and gives Rs 555,556. Multiplying by 1.09 or 1.04 wrongly shifts the timing of the first payment.

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