Question

A group of 10 items has arithmetic mean 6.If arithmetic mean of 4 of these items is 7.5 find mean of remaining items

Answer 1

answer=(10×6-4×7.5)/6,

=(60-30)/6,

=30/6=5

Answer 2

The mean of remaining items is 5.

Given that, the mean of 10 items is 6. So,

the total value of these 10 items is (6×10) = 60

Also given that out of the 10 items, 4 has a mean of 7.5.

So the total value of these 4 items is (4×7.5) = 30.

So, the value remaining = 60 - 30 = 30

No. of items remaining = 10 - 4 = 6.

So, arithmetic mean = Total value/ No. of items = 30/6 = 5

So, mean is 5.