Question
A bag contains 12 white and some black balls. If
the probability of drawing a black ball from the bag is thrice that of drawing a white ball, find the number of black balls in the bag.Solution
Number of white balls = 12
Let x be the number of black balls.
Total number of balls in the bag = 12 + x
Also, the probability of drawing a black ball from the bag is thrice that of drawing a white ball.
⇒ x/(12 + x) = 3[12/(12 + x)]
⇒ x = 3 × 12 = 36
Hence, the number of black balls in the bag = 36
More Probability Questions
- A list contains ten numbers. The average of the initial three values is 14, and the last five numbers have an average of 23. If the middle two numbers (4th...
The sum of four consecutive even numbers is 108. What is the sum of the squares of these numbers?
- Find the minimum number to subtract from 981243 so that the new number is exactly divisible by 9.
The numerator of a fraction is 9 less than its denominator. If the numerator is decreased by 4 and the denominator is increased by 2, then the denominat...
- What should be subtracted from (5/12) so that it becomes (1/8)?
Find the sum of all two-digit numbers that are exactly divisible by 6.
In an examination, the number of those who have passed and the number of those who failed were in the ratio of 40 : 7. If 7 more had appeared and the nu...
The smallest value of n, for which 2n + 1, is not a prime number, is
Find the unit digit of (62375Â - 7).
What is the least value of ‘a’ that should come in the number 5943a2, to make the number exactly divisible by 8?
Relevant for Exams:
