Question

There are 5 reb balls and some blue balls.the probability of picking a blue ball is double te probability of picking a red ball find number of blue balls

Answer 1

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

Answer 2

let the total blue ball be x
total red ball = 5
total number of balls = red balls + blue balls
total ball = x+5 .
p(getting blue ball)= x/x+5
p(getting red ball)= 5/x+5
according to the question, 
x/x+5 = 2× 5/x+5
cancelling both sides we get x= 10
∴ total blue ball = 10