Question

A bag contains some black and some white balls. If probability of a white ball is four times the probability of black ball, determine the number of black balls if total number of balls be 50.

Answer 1

answer is 10 balls
i hope it helps you

Answer 2

let x be no.of black balls and y be that of white balls
given 4x/x+y=y/x+y
4x=y
4x-y=0.......1
given total no.of balls =50
x+y=50......2

1+2
5x=50
x=10
sub x=10in 1
y=40
so no.of black balls=40
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