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The average marks obtained by a student in 6 subjects is 88. On subsequent verification it was found that the marks obtained by him in a subject was wrongly copied as 86 instead of 68. The correct average of the marks obtained by him is
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- 87
- 85
- 84
- 86
- 87
Correct Option: B
Here , The average marks obtained by a student in 6 subjects = 88
Correct sum of marks obtained by the student = 88 × 6 – 86 + 68
Correct sum of marks obtained by the student = 528 – 86 + 68 = 510
∴ Correct average = 510 ÷ 6 = 85
Second method to solve this question with the help of given formula :
Here, n = 6, m = 88 a = 68, b = 86
| Correct mean = m + | |
| n |
| Correct mean = 88 + | |
| 6 |
| Correct mean = 88 - | |
| 6 |
Correct mean = 85
