Question

The mean of 3 numbers is 7. The mean of

4 other numbers is 8. The mean of 5 other
numbers is 11. What is the mean of all 12
numbers?​

Answer 1

The mean of all 12 numbers is 9

Explanation:

Mean of 3 numbers = 7

Sum of the 3 numbers = 3 * 7 = 21

Mean of 4 other numbers = 8

Sum of the 4 other numbers = 4 * 8 = 32

Mean of 5 other numbers = 11

Sum of the 5 other numbers = 5 * 11 = 55

∴ Mean of all 12 numbers =
`(21+32+55)/(12)`

=
`(108)/(12)`

= 9

Answer 2

9.

Explanation:

The sum of the first 3 numbers = 3 * mean = 3*7 = 21.

For the other 4 , the mean = 4*8 = 32.

For the other 5, the mean = 5*11 = 55.

So the total sum for all 12 = 21 + 32 + 55

= 108.

Therefore the mean of all 12 = 108/12

=9.