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Railways PYQCBT 1 2016

RRB NTPC · Question 5

The mean of 15 observations is 14. Three more observations are included and the new mean becomes 13. The mean of three new observations is: A. 6 B. 7 C. 8 D. 11

  1. C

  2. D

  3. A

  4. B

Show answer & explanation

Answer: (A) C

Explanation

Sum of 15 observations = 15 × 14 = 210. Sum of 18 observations = 18 × 13 = 234. The three new observations total 24, so their mean is 8.