Question

a bag contains 5 red balls and some Blue Balls if the probability of drawing a blue ball is double that of red ball find the number of a blue balls in the back​

Answer 1

10

Explanation:

Let the number of blue balls be x.

Number of red balls = 5

Total number of balls = x + 5

P (getting a red ball) = 5/x+5

P (getting a blue ball) = x/x+5

Given that

2(5/x+5) = x/x+5

10(x+5) = x^(2) +5x

x^(2)-5x-50=0

x(x-10)(x+5)

Now either x-10 = 0 or x+5= 0

But number of balls cannot be negative.

Hence, the number of blue balls is 10.