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NDA 2026 · PYQ · Statistics / Mean · easy

If the mean of 20 observations, namely x₁, x₂, x₃, ..., x₂₀ is 1·414, then what is the value of Σᵢ₌₁²⁰ 100(2xᵢ + 4)?

  1. A.24168
  2. B.20828
  3. C.15248✓ Correct
  4. D.13656

Explanation

Mean = (Σxᵢ)/20 = 1.414, so Σxᵢ = 28.28. Then Σ 100(2xᵢ + 4) = 100[2Σxᵢ + 4·20] = 100[2(28.28) + 80] = 100[56.56 + 80] = 100(136.56) = 13656.
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