Question

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, determine the number of blue balls in the bag.

Answer 1

answer is 15
boz no of blue balls is double of red so blue balls are 10 and total balls are 15

Answer 2

let number of blue ball=x
total number of balls =5+x

probability of blue ball =x/5+x
probability of red ball =5/5+x

now
p(b)=2p(r)

x/5+x=2(5/5+x)
after solve this we get
x=10
so no. of blue balls is 10.