Multiple choice

The average of marks of 17 students in an examination was calculated as 71. But it was later found that the marks of one student had been wrongly entered as 65 instead of 56 and another as 24 instead of 50. The correct average is

  1. 70

  2. 71

  3. 72

  4. 73
Reveal answer Fill a bubble to check yourself
C Correct answer
AI explanation

The total net change in the sum of the marks is a decrease of 9 for the first student (56 minus 65) and an increase of 26 for the second student (50 minus 24). The overall change is an increase of 17 marks. Dividing this increase of 17 by the total number of students (17) results in an increase of 1 in the average. Adding this 1 to the initial average of 71 gives a correct average of 72.

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