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CAT
IMPORTANT
Earn 100

Tweleve persons are arranged in a row. The number of ways of selecting four persons so that no two persons sitting next to each other are selected is :

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Important Questions on Permutations & Combinations

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CAT
IMPORTANT
Quantum CAT Also Useful for XAT>Chapter 19 - SNAP>CMAT>Q 44
The number of n-bit (digits 0 and 1 ) strings having exactly k zeros with no two zeros consecutive is, where 2 k<n
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CAT
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Quantum CAT Also Useful for XAT>Chapter 19 - SNAP>CMAT>Q 45
A question paper has two parts-Part A and Part B. Part A contains 5 questions and part B has 4 . Each question in part A has an alternative. A student has to attempt atleast one question from each part. Find the number of ways in which the student can attempt the question paper.
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Quantum CAT Also Useful for XAT>Chapter 19 - SNAP>CMAT>Q 46
How many different vehicle licence plates can be made if the licences contain 2 letters of the English alphabet followed by a three digit number if repetitions are allowed?
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CAT
IMPORTANT
Quantum CAT Also Useful for XAT>Chapter 19 - SNAP>CMAT>Q 47
In the previous question (no. 46), how many different. plates can be formed if the repetitions are not allowed?
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CAT
IMPORTANT
Quantum CAT Also Useful for XAT>Chapter 19 - SNAP>CMAT>Q 48
2 m people are arranged along two sides of a long table with m chairs each side. r men wish to sit on one particular side and s on the other. In how many ways can they be seated? (r,s≤m)
MEDIUM
CAT
IMPORTANT
Quantum CAT Also Useful for XAT>Chapter 19 - SNAP>CMAT>Q 49
Management city has m parallel roads running East-West and n parallel roads running North-South. How many shortest possible routes are possible to go from one corner of the city to its diagonally opposite corner?
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CAT
IMPORTANT
Quantum CAT Also Useful for XAT>Chapter 19 - SNAP>CMAT>Q 50
Priyanka has 11 different toys and Supriya has 8 different toys. Find the number of ways in which they can exchange their toys so that each keeps her initial number of toys.
MEDIUM
CAT
IMPORTANT
Quantum CAT Also Useful for XAT>Chapter 19 - SNAP>CMAT>Q 51
The sum of the numbers of the nth  term of the series (1)+(1+2)+(1+2+3)+(1+2+3+4)+… (1+2+3+…n):