While calculating the mean of 3 single-digit numbers, Xavier mistakenly replaced the number 6 by 9, and obtained the mean as 5. Find the actual mean of the data set.
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Solution
The correct option is A 4 While calculating the mean of 3 single-digit numbers, Xavier replaced 6 by 9, and obtained the mean as 5.
Consider, the other 2 single-digit numbers are []and[].
As Xavier obtained the mean of data set {[],[],9} as 5, we can write
[]+[]+93=5
⇒[]+[]+93×3=5×3
(multiplying 3 in both sides)
⇒[]+[]+9=15
⇒[]+[]+9−9=15−9
(substracting 9 from both sides)
⇒[]+[]=6
Need to find: Actual mean of the data set {[],[],6}, i.e.,