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 deck of cards is divided into 2 small decks with unequal number of cards in each deck. The probability of selecting a red ace from the 1st deck is given to be 1 11 and that of selecting a black card from the 2nd deck is 3 5 . It is also known that the 2nd deck does not have any red ace. If the ratio of red to black cards in the first deck is given to be 6:5, then what will be the probability of selecting a card which is not black?

  1. 6 11

  2. 7 11

  3. 5 13

  4. 6 13

  5. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice

From a pack of 52 cards, all face cards are removed and four cards are drawn. The probability that they are of different suit and different denomination is

  1. ( 9 10 ) 4

  2. 10 × 9 × 8 × 7 10 4

  3. 10 × 9 × 8 × 7 40 C 4

  4. ( 9 13 ) 4

  5. 9 10
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

After removing the 12 face cards, 40 cards remain, with 10 cards in each denomination. The number of favorable selections is 10 x 9 x 8 x 7, because the four cards must have different denominations and different suits. Dividing by the total number of four-card selections, C(40,4), gives the expression in option C.

Multiple choice

Cards are drawn one by one from a deck of 52 cards without replacement. The chance that four cards are drawn before the first ace (fifth card) is

  1. 4 48 × 1 4

  2. 48 × 47 × 46 × 45 × 4 52 × 52 × 52 × 52 × 52 × 4 52

  3. 48 × 47 × 46 × 45 52 × 51 × 50 × 49 × 44 48

  4. 48 × 47 × 46 × 45 52 × 51 × 50 × 49 × 4 48

  5. 1 12
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

To have four cards before the first ace, the first four cards must be non-aces (48/52 * 47/51 * 46/50 * 45/49) and the fifth card must be an ace (4/48).