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# 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.

It is given that the total number of red balls = 5

Let the total number of blue balls = x

So, the total no. of balls = x + 5

P(E) = $$\frac{(Number of favourable outcomes}{ Total number of outcomes}$$

P (drawing a blue ball) $$= \ \frac{x}{x \ + \ 5}$$ ..... (i)

Similarly,

P (drawing a red ball) $$= \ \frac{5}{x \ + \ 5}$$ ....(ii)

From equation (i) and (ii)

x = 10

So, the total number of blue balls = 10