Q. 225.0( 13 Votes )

# A box contains 12 balls out of which x are black. If one ball is drawn at random from the box, what is the probability that it will be a black ball?

If 6 more black balls are put in the box, the probability of drawing a black ball is now double of what it was before. Find x.

Answer :

**Given:** Total balls = 12

Black balls = x

**Concept Used:**

**Explanation:**

Probability of drawing a black ball, P(black)

Now 6 black balls are added to the box, therefore,

Total balls = 12 + 6 = 18

Black balls = x + 6

Let the new probability be P(new)

Now,

P(new) = 2.P(black)

Therefore,

Cross multiplying, we get,

6x + 36 = 18x18x - 6x = 36

12x = 36

x = 3

**Hence, value of x is 3.**

Rate this question :

How useful is this solution?

We strive to provide quality solutions. Please rate us to serve you better.

PREVIOUSRed queens and blackjacks are removed from a pack of 52 playing cards. A card is drawn at random from the remaining cards, after reshuffling them. Find the probability that the card is drawn is(i) a king(ii) of red colour(iii) a face card(iv) a queenNEXTA bag contains cards numbered from 1 to 49. A card is drawn from the bag at random, after mixing the card thoroughly. Find the probability that the number on the drawn card is(i) an odd number(ii) a multiple of 5(iii) a perfect square(iv) an even prime number.

Related Videos

Quiz | Imp. Qs. of Probability37 mins

Let's understand Probability40 mins

When Chance is called Probability48 mins

Try our Mini CourseMaster Important Topics in 7 DaysLearn from IITians, NITians, Doctors & Academic Expertsview all courses

Dedicated counsellor for each student

24X7 Doubt Resolution

Daily Report Card

Detailed Performance Evaluation

RELATED QUESTIONS :

Which of the following amongst the given options cannot be the probability of an event:

(i) 1.01 (ii) 67%

(iii) -0.5 (iv)

(v) 0.3

KC Sinha - Mathematics