The mean of 50 numbers is 30. Later it was discovered that

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The mean of 50 numbers is 30. Later it was discovered that two entries were wrongly entered as 82 and 13 instead of 28 and 31. Find the correct mean.

1. 36.12
2. 30.66
3. 29.28
4. 38.21

Correct Option: C

Required average = 30 +	(28 + 31 - 82 - 13)
	50

Required average = 30 +		-	36
			50

Required average = 30 – 0.72 = 29.28
Second method to solve this question with the help of given formula :
Here, n = 50, m = 30 , a = 28, b = 31 , p = 82, q = 13

Correct Average = m +	(a + b - p - q)
	n

Correct Average = 30 +	(28 + 31 - 82 - 13)
	50

Correct Average = 30 +		-	59 - 95
			50

Correct Average = 30 -	36
	50

Correct Average = 30 – 0.72 = 29.28