NCERT Solutions
Class 11 Maths
Permutations and Combinations
Electric charges

Ex.7.1 Q.1

How many 3-digit numbers can be formed from the digits 1, 2, 3, 4 and 5 assuming that           

(1) repetition of the digits is allowed?                 

(2) repetition of the digits is not allowed?

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Ex.7.1 Q.2

How many 3-digit even numbers can be formed from the digits 1, 2, 3, 4, 5, 6 if the digits can be repeated?

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Ex.7.1 Q.3

How many 4-letter code can be formed using the first 10 letters of the English alphabet, if no letter can be repeated?

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Ex.7.1 Q.4

How many 5–digit telephone numbers can be constructed using the digits 0 to 9

if each number starts with 67 and no digit appears more than once?

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Ex.7.1 Q.5

A coin is tossed 3 times and the outcomes are recorded. How many possible outcomes are there?

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Ex.7.2 Q.1

Evaluate (1) 8!                                        

(2) 4! – 3!

 

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Ex.7.2 Q.2

Is 3! + 4! = 7!?

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Ex.7.2 Q.3

Compute 8! ÷ (6! × 2!)

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Ex.7.2 Q.4

If (1 ÷ 6!) + (1 ÷ 7!) = (x ÷ 8!), find x.

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Ex.7.2 Q.5

Evaluate n! ÷ (n - r)! when

(1) n = 6, r = 2                                 

(2) n = 9, r = 5

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Ex.7.3 Q.1

How many 3-digit numbers can be formed by using the digits 1 to 9 if no digit is repeated?

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Ex.7.3 Q.2

How many 4-digit numbers are there with no digit repeated?

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Ex.7.3 Q.3

How many 3-digit even numbers can be made using the digits 1, 2, 3, 4, 6, 7, if no digit is repeated?

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Ex.7.3 Q.4

Find the number of 4-digit numbers that can be formed using the digits 1, 2, 3, 4, 5 if no digit is repeated.

How many of these will be even?

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Ex.7.3 Q.5

From a committee of 8 persons, in how many ways can we choose a chairman and a

vice chairman assuming one person cannot hold more than one position?

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Ex.7.3 Q.6

Find n if n-1P3: nP4 = 1: 9

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Ex.7.3 Q.7

Find r if (1) 5Pr = 2 × 6Pr-1                                

(2) 5Pr = 6Pr-1 

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Ex.7.3 Q.8

How many words, with or without meaning, can be formed using all the letters of the word

EQUATION, using each letter exactly once?

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Ex.7.3 Q.9

How many words, with or without meaning can be made from the letters of the word

MONDAY, assuming that no letter is repeated, if

(1) 4 letters are used at a time,

(2) all letters are used at a time,

(3) all letters are used but first letter is a vowel?

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Ex.7.3 Q.10

In how many of the distinct permutations of the letters in MISSISSIPPI do the four I’s not come together?

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Ex.7.3 Q.11

In how many ways can the letters of the word PERMUTATIONS be arranged if the

(1) words start with P and end with S,

(2) vowels are all together,

(3) there are always 4 letters between P and S?

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Ex.7.4 Q.1

If nC8 = nC2, find nC2

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Ex.7.4 Q.2

(1) 2nC3: nC3 = 12: 1                                           

(2) 2nC3: nC3 = 11: 1

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Ex.7.4 Q.3

How many chords can be drawn through 21 points on a circle?

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Ex.7.4 Q.4

In how many ways can a team of 3 boys and 3 girls be selected from 5 boys and 4 girls?

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Ex.7.4 Q.5

Find the number of ways of selecting 9 balls from 6 red balls, 5 white balls and 5 blue balls

if each selection consists of 3 balls of each colour.

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Ex.7.4 Q.6

Determine the number of 5 card combinations out of a deck of 52 cards if

there is exactly one ace in each combination.

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Ex.7.4 Q.7

In how many ways can one select a cricket team of eleven from 17 players in which only 5

players can bowl if each cricket team of 11 must include exactly 4 bowlers?

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Ex.7.4 Q.8

A bag contains 5 black and 6 red balls. Determine the number of ways in which 2 black and 3 red balls can be selected.

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Ex.7.4 Q.9

In how many ways can a student choose a programme of 5 courses if 9 courses are available

and 2 specific courses are compulsory for every student?

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Ex.Misc.Q.1

How many words, with or without meaning, each of 2 vowels and 3 consonants

can be formed from the letters of the word DAUGHTER?

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Ex.Misc.Q.1

How many words, with or without meaning, can be formed using all the letters of the word EQUATION

at a time so that the vowels and consonants occur together?

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Ex.Misc.Q.3

A committee of 7 has to be formed from 9 boys and 4 girls.

In how many ways can this be done when the committee consists of:                                                                                                  

(1) exactly 3 girls?                         

(2) at least 3 girls?                         

(3) at most 3 girls?

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Ex.Misc.Q.4

If the different permutations of all the letter of the word EXAMINATION are listed as in a dictionary,

how many words are there in this list before the first word starting with E?

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Ex.Misc.Q.5

How many 6-digit numbers can be formed from the digits 0, 1, 3, 5, 7 and 9

which are divisible by 10 and no digit is repeated?

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Ex.Misc.Q.6

The English alphabet has 5 vowels and 21 consonants. How many words with two different vowels

and 2 different consonants can be formed from the alphabet?

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Ex.Misc.Q.7

In an examination, a question paper consists of 12 questions divided into two parts i.e.,

Part I and Part II, containing 5 and 7 questions, respectively.

A student is required to attempt 8 questions in all, selecting at least 3 from each part.

In how many ways can a student select the questions?

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Ex.Misc.Q.8

Determine the number of 5-card combinations out of a deck of 52 cards if each selection of 5 cards has exactly one king.

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Ex.Misc.Q.9

It is required to seat 5 men and 4 women in a row so that the women occupy the even places.

How many such arrangements are possible?

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Ex.Misc.Q.10

From a class of 25 students, 10 are to be chosen for an excursion party.

There are 3 students who decide that either all of them will join or none of them will join.

In how many ways can the excursion party be chosen?

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Ex.Misc.Q.11

In how many ways can the letters of the word ASSASSINATION be arranged so that all the S’s are together?

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Complete NCERT Solutions: Classes 6 to 12, All Chapters

NCERT Solution for class 6
NCERT Solution for class 7
NCERT Solution for class 8
NCERT Solution for class 9
NCERT Solution for class 10
NCERT Solution for class 11
NCERT Solution for class 12

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