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There are 12 boys and 8 girls in a tuition centre. If three of among them scored first rank, then find the probability that among these three one is a girl and the other two are boys.

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Important Questions on Counting Principles

EASY

Quantitative Aptitude>Arithmetic>Counting Principles>Probability

Two dices are rolled. If both dices have six faces numbered

1, 2, 3, 5, 7

and

11,

then the probability that the sum of the numbers on the top faces is less than or equal to

8

is:

EASY

Quantitative Aptitude>Arithmetic>Counting Principles>Probability

In a college, $\frac{1}{5} t h$ of the girls and $\frac{1}{8} th$ of the boys took part in a social camp. The total number of students in the college took part in the camp is:

HARD

Quantitative Aptitude>Arithmetic>Counting Principles>Probability

The probability that a randomly chosen

5

- digit number is made from exactly two digits is :

MEDIUM

Quantitative Aptitude>Arithmetic>Counting Principles>Probability

The numbers

a

and

b

are choosen randomly from the set

\{1, 2, 3, 4, 5, 6\}

with replacement such that

a

and

b

are prime to each other. Then the probability that is

EASY

Quantitative Aptitude>Arithmetic>Counting Principles>Probability

There are

3

red balls,

4

blue balls and

5

white balls.

2

balls are chosen randomly. Find the probability that one is red and the other is white.

MEDIUM

Quantitative Aptitude>Arithmetic>Counting Principles>Probability

a

is an integer lying in

[- 11, 14]

, then the probability that the graph o

y = x^{2} + 2 (a + 6) x + a + 62

is strictly above the

x

-axis is

MEDIUM

Quantitative Aptitude>Arithmetic>Counting Principles>Probability

Two letters are chosen from the letters of the word 'EQUATIONS'. The probability that one is vowel and the other is consonant is

EASY

Quantitative Aptitude>Arithmetic>Counting Principles>Probability

Which of the following cannot be the probability of an event?

MEDIUM

Quantitative Aptitude>Arithmetic>Counting Principles>Probability

A bag contains

3

red balls,

5

yellow balls and

7

pink balls. If one ball is drawn at random from the bag, what is the probability that it is either pink or red?

MEDIUM

Quantitative Aptitude>Arithmetic>Counting Principles>Probability

Let

a

and

b

2

consecutive integers selected from the first

20

natural numbers. The probability that

\sqrt{a^{2} + b^{2} + a^{2} b^{2}}

is an odd positive integer is

MEDIUM

Quantitative Aptitude>Arithmetic>Counting Principles>Probability

Two persons

A

and

B

throw a die alternatively till one of them gets a three and wins the game. Find their respective probabilities of winning.

EASY

Quantitative Aptitude>Arithmetic>Counting Principles>Probability

A bag contains

6

black and

8

white balls. One ball is drawn at random. What is the probability that the ball drawn is white?

EASY

Quantitative Aptitude>Arithmetic>Counting Principles>Probability

There are $6$ defective items in a sample of $20$ items. One item is drawn at random. The probability that it is a non-defective item is:

MEDIUM

Quantitative Aptitude>Arithmetic>Counting Principles>Probability

Two numbers

x

and

y

are chosen at random from the set {

x : 0 \leq x \leq 10, x

is an integer). The probability for

|x - y| = 5

EASY

Quantitative Aptitude>Arithmetic>Counting Principles>Probability

If $P (A) = \frac{2}{3}$ , $P (\bar{A})$ is

EASY

Quantitative Aptitude>Arithmetic>Counting Principles>Probability

In a given village there are only three sizes of families: families with

2

members, familes with

4

members and families with

6

members. The proportion of families with

2, 4

and

6

members are roughly equal. A poll is conducted in this village wherein a person is chosen at random and asked about his/her family size. The average family size computed by sampling

1000

such persons from the village would be closest to

EASY

Quantitative Aptitude>Arithmetic>Counting Principles>Probability

A die is thrown three times and the sum of the three numbers thrown is

15

, then the probability that the first throw was a four is

MEDIUM

Quantitative Aptitude>Arithmetic>Counting Principles>Probability

Six persons $A, B, C, X, Y & Z$ go for an interview. What is the probability of selection of $A$ and $Y$ in the interview?

MEDIUM

Quantitative Aptitude>Arithmetic>Counting Principles>Probability

There are

6

red balls and

4

yellow balls in a bag. Two balls are simultaneously drawn at random. What is the probability that both the balls are of same colour?

EASY

Quantitative Aptitude>Arithmetic>Counting Principles>Probability

What is the probability that a number selected from numbers

1, 2, 3,_______30

, is a prime number, when each of the given numbers is equally likely to be selected?

There are 12 boys and 8 girls in a tuition centre. If three of among them scored first rank, then find the probability that among these three one is a girl and the other two are boys.

Important Questions on Counting Principles

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