Class 11 Maths
Permutations and Combinations
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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