2022 · Q67
Mean marks of 50 students were found to be 78.4. But later it was detected that 95 was misread as 59 and 25 was misread as 52. What is the difference between correct mean and incorrect mean?
Elementary MathematicsStatistics
- A0.04
- B0.08
- C0.12
- D0.18
Explanation
The corrected total exceeds the wrong total by (95−59)+(25−52) = 9, so the mean rises by 9/50 = 0.18. The two misreadings partly cancel (+36 and −27), leaving a net +9. The keyed option is D.