Question

A bag contains x red balls, (x + 5) blue balls and (3x + 10) white balls. If the probability of drawing a blue ball is 2/9, what is the number of white balls?

(a) 15

(b) 20

(c) 35

(d) 55

Answer 1

Correct option is (d) 55

Total balls = x + x + 5 + 3x + 10

= 5x + 15

Fav. balls = x + 5

\(\therefore \frac{x + 5}{5x + 15} = \frac 29\)

⇒ \(9x + 45 = 10x + 30\)

⇒ \(x = 15\)

\(\therefore \) Number of white balls = 3x + 10

= 3(15) + 10

= 45 + 10

= 55

Answer 2

(x+5)/(5x+15) = 2/9     =>    x = 15

white balls = 3x + 10 = 45 + 10 = 55

Correct answer: (d) 55