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NDA 2025 Maths · Mathematics · Statistics · medium

The weighted arithmetic mean of the marks 40, 50, 60 with weights 1, 2, 2 respectively is

Single correct option

The weighted arithmetic mean of the marks 4040, 5050, 6060 with weights 11, 22, 22 respectively is
  1. A. 5050
  2. B. 5454
  3. C. 5252
  4. D. 52.552.5
Show answer and solution

Answer: (C) 5252

Weighted mean =1⋅40+2⋅50+2⋅601+2+2=2605=52=\frac{1\cdot40+2\cdot50+2\cdot60}{1+2+2}=\frac{260}{5}=52. The simple mean 5050 ignores the weights, 5454 comes from putting weights 1,2,31,2,3 against the wrong scores, and 52.552.5 divides by a wrong total. Always divide by the sum of weights.
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Original question written in the NDA 2025 Maths pattern and checked twice for the correct answer. Not an official question paper. How we write and check questions · Corrections policy · Report a mistake