Q262 / 270 · NDA 2021 (Phase 1) · Mathematics

The mean of 12 observations is 75 . If two observations are discarded, then the mean of the remaining observations is 65 . What is the mean of the discarded observations?

  • A
    $250$
  • Correct answer
    B
    $125$
  • C
    $120$
  • D
    Cannot be determined due to insufficient data

Solution

Mean of discarded observation $=\frac{\text { Sum of } 12 \text { observation }- \text { Sum of } 10 \text { observation }}{2}$ $=\frac{12 \times 75-10 \times 65}{2}=125$

Hence, the correct answer is option: 'B'.

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