Q206 / 270 · NDA 2013 (Phase 2) · Mathematics

The mean of 20 observations is 15. On checking, it was found that two observation were wrongly copied as 3 and 6. If wrong observations are replaced by correct values 8 and 4 , then the correct mean is

  • A
    15
  • Correct answer
    B
    15.15
  • C
    15.35
  • D
    16

Solution

Difference in values $=(8+4)-(6+3)=3$ Mean difference $=\frac{3}{20}=0.15$ Hence, correct mean $=15.15$

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

Relevant Questions