CA Foundation · Quantitative Aptitude · Measures of Central Tendency and Dispersion
The mean of 8 observations is 25. If one observation, recorded as 18, is found to be actually 34, what is the correct mean?
The correct mean is 27. The original total is 8 × 25 = 200; replacing 18 with 34 raises the total by 16 to 216, and dividing by 8 observations gives 27.
- A27Correct
- B25
- C23
- D29
Explanation
Original sum = 8 × 25 = 200. Correct sum = 200 − 18 + 34 = 216. Correct mean = 216/8 = 27. Option 29 results from adding the full 34 without removing the wrong value... no, it wrongly adds 16 twice; 25 ignores the correction.
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