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CMA Foundation · Fundamentals of Business Mathematics and Statistics · Index Numbers and Time Series

A time series is analysed by the multiplicative model. For a quarter, the deseasonalised sales are ₹ 80,000 and the seasonal index is 125. What are the actual sales for that quarter?

Actual sales are ₹ 1,00,000. Under the multiplicative model, deseasonalised sales equal actual sales divided by the seasonal index as a ratio, so actual equals 80,000 multiplied by 1.25. Dividing instead would wrongly give ₹ 64,000.

  1. A₹ 64,000
  2. B₹ 1,00,000Correct
  3. C₹ 80,125
  4. D₹ 1,25,000

Explanation

Deseasonalised value = actual / (index/100), so actual = 80,000 × 1.25 = 1,00,000. The option ₹ 64,000 comes from dividing by 1.25 instead of multiplying, which is the reverse operation.

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