If first two items are increased by 3 and last two items are reduced by 3, then what will be the new mean?

Question

Check the properties of arithmetic mean for the example given below:

X

3

6

9

12

15

If first two items are increased by 3 and last two items are reduced by 3, then what will be the new mean?

Answer 1

If the first two items is increased by 3, then the numbers will be 3 + 3, 6 + 3 ⇒ 6, 9. 

If last two numbers are decreased by 3, then the numbers will be 12 – 3, 15 – 3 ⇒ 9,12.

There is no change in the mean.