#### Probability Question & Answers

An unbiased die is rolled. Find the probability of getting a multiple of 3?

A) 1/6 | B) 1/3 |

C) 5/6 | D) None of these |

Explanation:

S = { 1, 2, 3, 4, 5, 6 }

=> n(S) = 6

E = { 3, 6}

=> n(E) = 2

Therefore, P(E) = 2/6 =1/3

Subject: Probability - Quantitative Aptitude - Arithmetic Ability

- Related Questions

A letter iws takenout at random from 'ASSISTANT' and another is taken out from 'STATISTICS'. The probability that they are the same letter is :

A) 35/96 | B) 19/90 |

C) 19/96 | D) None of these |

Explanation:

Here N and C are not common and same letters can be A, I, S, T. Therefore

Probability of choosing A = = 1/45

Probability of choosing I = = 1/45

Probability of choosing S = = 1/10

Probability of choosing T = = 1/15

Hence, Required probability =

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Subject: Probability - Quantitative Aptitude - Arithmetic Ability

8 couples (husband and wife) attend a dance show "Nach Baliye' in a popular TV channel ; A lucky draw in which 4 persons picked up for a prize is held, then the probability that there is atleast one couple will be selected is :

A) 8/39 | B) 15/39 |

C) 12/13 | D) None of these |

Explanation:

P( selecting atleast one couple) = 1 - P(selecting none of the couples for the prize)

=

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Subject: Probability - Quantitative Aptitude - Arithmetic Ability

A bag contains 4 red and 3 black balls. A second bag contains 2 red and 4 black balls. One bag is selected at random. From the selected bag, one ball is drawn. Find the probability that the ball drawn is red.

A) 23/42 | B) 19/42 |

C) 7/32 | D) 16/39 |

Explanation:

A red ball can be drawn in two mutually exclusive ways

(i) Selecting bag I and then drawing a red ball from it.

(ii) Selecting bag II and then drawing a red ball from it.

Let E1, E2 and A denote the events defined as follows:

E1 = selecting bag I,

E2 = selecting bag II

A = drawing a red ball

Since one of the two bags is selected randomly, therefore

P(E1) = 1/2 and P(E2) = 1/2

Now, = Probability of drawing a red ball when the first bag has been selected = 4/7

= Probability of drawing a red ball when the second bag has been selected = 2/6

Using the law of total probability, we have

P(red ball) = P(A) =

=

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Subject: Probability - Quantitative Aptitude - Arithmetic Ability

Ajay and his wife Reshmi appear in an interview for two vaccancies in the same post. The Probability of Ajay's selection is 1/7 and that of his wife Reshmi's selection is 1/5. What is the probability that only one of them will be selected?

A) 5/7 | B) 1/5 |

C) 2/7 | D) 2/35 |

Explanation:

P( only one of them will be selected)

= p[(E and not F) or (F and not E)]

=

=

=

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Subject: Probability - Quantitative Aptitude - Arithmetic Ability

The probabilities that a student will receive an A, B, C or D grade are 0.4, 0.3 , 0.2 and 0.1 respectively. Find the probability that a student will receive Atleast B grade.

A) 0.21 | B) 0.3 |

C) 0.7 | D) None of these |

Explanation:

P(atleast B) = P( B or A) = P(B) + P(A) = (0.3) + (0.4) = 0.7

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Subject: Probability - Quantitative Aptitude - Arithmetic Ability