The mean of scores obtained by 50 students is found to be 79.5. Later on, it was found that the score of one student was read as 94 in place of 49 and the score of another student was read as 69 in place of 89. Find the correct mean.
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 79
A misread score changes the total, not the number of students. So the wrong total is found from the mean, corrected, and divided again by 50.
Total with the misread scores \(=50\times79.5=3975\)
First score: 94 was taken instead of 49, so the total is 45 too high
Second score: 69 was taken instead of 89, so the total is 20 too low
Correct total \(=3975-45+20=3950\)
Correct mean \(=3950\div50=\) 79