# NCERT Class 12-Mathematics: Chapter –13 Probability Part 19

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**Question 77:**

Assume that in a family, each child is equally likely to be a boy or a girl. A family with three children is chosen at random. The probability that the eldest child is a girl given that the family has at least one girl is

(A)

(B)

(C)

(D)

**Answer: (D)**

**Question 78:**

A die is thrown and a card is selected at random from a deck of playing cards. The probability of getting an even number on the die and a spade card is

(A)

(B)

(C)

(D)

**Answer: (C)**

**Question 79:**

A box contains 3 orange balls, 3 green balls and 2 blue balls. Three balls are drawn at random from the box without replacement. The probability of drawing 2 green balls and one blue ball is

(A)

(B)

(C)

(D)

**Answer: (A)**

**Question 80:**

A flashlight has batteries out of which are dead. If two batteries are selected without replacement and tested, the probability that both are dead is

(A)

(B)

(C)

(D)

**Answer: (D)**

**Question 81:**

Eight coins are tossed together. The probability of getting exactly heads is

(A)

(B)

(C)

(D)

**Answer: (B)**

**Question 82:**

Two dice are thrown. If it is known that the sum of numbers on the dice was less than 6, the probability of getting a sum , is

**Answer: (C)**

**Question 83:**

Which one is not a requirement of a binomial distribution?

(A) There are outcomes for each trial

(B) There is a fixed number of trials

(C) The outcomes must be dependent on each other

(D) The probability of success must be the same for all the trials

**Answer: (C)**

**Question 84:**

Two cards are drawn from a well shuffled deck of playing cards with replacement. The probability, that both cards are queens, is

(A)

(B)

(C)

(D)

**Answer: (A)**

**Question 85:**

The probability of guessing correctly at least out of answers on a true-false type examination is

(A)

(B)

(C)

(D)

**Answer: (B)**