Q5 of 14 Page 15

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, find the number of blue balls in the bag.

Let the number of blue balls in the bag be x. The number of red balls in the bag is 5.
P(Drawing a blue ball) =
P( Drawing a red ball) =
P( Drawing a blue ball) = 2 × P(Drawing a red ball) ⇒ = 2 ×
i.e x = 10

The number of blue balls in the bag is 10.

More from this chapter

All 14 →
3 17 cards numbered 1, 2, 3, ..., 16, 17 are put in a box and mixed thoroughly. One person draws a card from the box. Find the probability that the number on the card is         
(i) odd.                       
(ii) a prime              
(iii) divisible by 3     
(iv) divisible by 3 and 2 both 4 A die is thrown once. Find the probability of getting
(i) an even number
(ii) a number greater than 3
(iii) a number between 3 and 6 6 A bag contains 12 balls out of which x are white.
(i) If one ball is drawn at random, what is the probability that it will be a white ball?
(ii) If 6 more white balls are put in the bag, the probability of drawing a white ball will be double than that in (I case). Find x. 7 Five male and three female candidates are available for selection as on manager in a company. Find the probability that male is selected.