Question

a bag contains 5 red balls and some blue balls. If the probability of drawing a blue ball from the bag is four times that of a red ball, then find the number of blue balls in the bag.

Answer 1

let no.of blue balls=x
toal no.of balls=5+x
p(b)=x/5+x
p(r)=5/5+x
now,
p(b)=2p(r)
solving we get x=10.

Answer 2

hope it helps..........