A bag contains 5 red balls and some blue balls. If the probability of drawing a blue ball at random from the bag is three times that of a red ball, find the number of blue balls in the bag?

15

Step-by-step explanation:

Total # of balls = red+blue. Three times = 3 * redballs (5), hence 3 * 5 = 15

10

Step-by-step explanation:

Let number of blue balls = x

Total number of balls = 5+x

Probability for a red ball = x+5/5

Probability for a blue ball = 5+x/x

According to the question 5+x/x=2 (x+5/5) ⇒x=10 ∴

Number of blue balls=10.