# 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, then find the number of blue balls in the bag.

Let number of blue balls be x.

Red balls are 5.

Total balls = 5 + x

P(E) = (Number of favourable outcomes/ Total number of outcomes)

∴ P (drawing a blue ball) = [x/(x+5)] ——–(i)

Similarly,

P (drawing a red ball) = [5/(x+5)] ——–(i)

From equation (i) and (ii)

x = 10

Hence, the total number of blue balls = 10