Sum value variance

[Matrix]

Variance is sum of square of deviation from the mean.

Mean of sum value=(£g)
Standard deviation of sum value=S=(£m)
Variance of sum value=s2=£mx£m

i.e.
Lottery in C(42,6)
£g=129
£m=27.8208554864
Variance=774=£mx£m

Question:

£mx£m=6£g....129x6=774....Why?

Who can prove them?

 

[Matrix]

Lottery in C(49,6)
£g=150
Variance=900=£mx£m
£m=30
Question:

£mx£m=6£g....150x6=900....Why?

Who can prove them?