Question 123

The average marks of 14 students was 71. It was later found that the marks of one of the students has been wrongly entered as 42 instead of 56 and of another as 74 instead of 32. What is the correct average?

Solution

given that the average of 14 students is 71

so sum of the marks = 14*71

=>994

given that 42 is entered instead of 56 and 74 instead of 32

so 994+(56-42)-(74-32)

994+14-42=966

now the average is $$\frac{966}{14}=69$$

so, the correct average is 69

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