fluke wrote:

Baten80 wrote:

Why will we multiply the sum of column by 7?

Take 1 row at a time

1st row: Total = Average*Number of elements = 4*7

2nd row: Total = Average*Number of elements = -8*7

3rd row: Total = Average*Number of elements = 12*7

4th row: Total = Average*Number of elements = -16*7

5th row: Total = Average*Number of elements = 20*7

6th row: Total = Average*Number of elements = -24*7

7th row: Total = Average*Number of elements = 28*7

Add them up:

4*7+(-8)*7+12*7+(-16)*7+20*7+(-24)*7+28*7

Take 7 common:

7(4-8+12-16+20-24+28)

Hello Fluke

just to make sure I understood

as thoses questions look tricky and time consuming

first each line is a AP Progression

you use the average formula in reverse to find the sum

since in an AP Progression the mean or average is the same as median number

and then you factorise by 7 to complete the sum and multiply it by 7 as each line is a multiple of 7

right ?

Thanks for help

best regards