Question

can u help me to solve this

Answer 1

hi ,

let number of total balls be x

P(B) + P(W) = 1
P(W) = 8/x
P(B) = 1 - 8/x

Given
P(B) = 4*P(W)
1- 8/x = 4*8/x
1 = (32+8) / x
x = 40

so number of black balls
= x - 8
= 32 balls

Hope it helped.
Let me know if any doubts.
Cheers !!!