Quantitative Aptitude

Probability

1,860 Questions
All Sample Space Setup 558 Permutation & Combination Counting 288 Multiplication Theorem (AND) 234 Addition Theorem (OR) 151 At Least One Probability 134 Complement Rule (P(Not A)) 130 Drawing Without Replacement 126 Conditional Probability 75 Bayes' Theorem 69 Drawing With Replacement 49 Success and Failure Rates 46

Probability Questions

Multiple choice

A die is rolled 3 times. The probability of getting a larger number than the previous number is

  1. 5/216

  2. 5/54

  3. 1/6

  4. 5/36

  5. None
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The first die can show any numbers from 1 of 6. Second can show numbers greater than the first and third acn show greater than the second. Number of ways = (1,2,3) (1,2,4)(1,2,5)(1,2,6) (1,3,6) (1,4,6) (1,3,5) (1,4,5) (1,4,6)(1,5,6), (2,3,6) (2,3,5)(2,3,4) (2,4,5) (2,4,6) (2,5,6) (3,4,5) (3,4,6) (3,5,6) (4,5,6). Hence, probability = 20/216 = 5/54.

Multiple choice

A bag contains 12 balls of two different colors, out of which x are white. One ball is drawn at random. If 6 more white balls areput in the bag, the probability of drawing a white ball now will be double that of the previous probability of drawing a white ball. Then, the value of x is _____.

  1. 3

  2. 4

  3. 5

  4. 6
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

1st Case x are white 12-x are non-white P(white) =x/12 2nd Casex+6 are white P(white)=(x+6)/18 According to question (x+6)/18= 2(x/12) Solve to get x=3