Question

2.A bag contains 5 red balls and some blue balls.If the probability of drawing a blue ball is double that of a red ball,find the number of blue balls in the bag.(Ans.10)

Answer 1

red balls=5
blue balls=x
p(red)=5\(5+x)
p(blue)=x\(5+x)

p(blue)=2[p(red)]
x\(5+x)=10\(5+x)
so x=10 i.e. no of blue balls is 10