Permutations And Combinations CBSE Questions & Answers

Permutations And Combinations

This is Mathematics Class 11 Permutations and Combinations CBSE Questions & Answers. There are 15 questions in this test with each question having around four answer choices.

Questions & Answers

1
The number of three digit numbers having atleast one digit as 5 is
  • A
    252
    Correct
  • B
    648
  • C
    225
  • D
    246
2
5 boys and 5 girls are to be seated around a table such that boys and girls sit alternately. The number of ways of seating them is
  • A
    \(5!{\text{ }} \times {\text{ }}4!\)
    Correct
  • B
    none of these
  • C
    \(4!{\text{ }} \times {\text{ }}4!\)
  • D
    \(5!{\text{ }} \times {\text{ }}5!\)
3
The total number of numbers from 1000 to 9999 (both inclusive) that do not have 4 different digits
  • A
    none of these.
  • B
    4464
    Correct
  • C
    9000
  • D
    4536
4
If P(n,r) = C(n,r) then
  • A
    none of these
  • B
    r = 0 or 1
    Correct
  • C
    r = 1 or n
  • D
    n = r
5
2.6.10.14……upto 50 factors is equal to
  • A
    \(100!\)
  • B
    \({{100!} \over {50!}}\)
    Correct
  • C
    none of these
  • D
    \(50!\)
6
The greatest power of 10 that divides 1000!
  • A
    none of these
  • B
    429
  • C
    111
  • D
    249
    Correct
7
The number of arrangements that can be formed by all the letters of the word “LAUGHTER “is
  • A
    C(8,8)
  • B
    P(8,8)
    Correct
  • C
    \({8^8}\)
  • D
    none of these.
8
A convex polygon of n sides has twice as many diagonals as the number of sides. The value of n is
  • A
    8
  • B
    6
  • C
    5
  • D
    7
    Correct
9
The number of all odd (positive) divisors of 36000 is
  • A
    12
    Correct
  • B
    none of these
  • C
    60
  • D
    72
10
The number of three digit numbers having atleast one digit as 7 is
  • A
    252
    Correct
  • B
    none of these
  • C
    648
  • D
    225
11
The number of all 4 digited different numbers that can be formed by using the digits 0, 2, 3, 5, 8, 9, is
  • A
    360
  • B
    300
  • C
    none of these
  • D
    1080
    Correct
12
\(0!\) is always taken as
  • A
    none of these
  • B
    0
  • C
    \(\infty \)
  • D
    1
    Correct
13
\({1 \over {9!}} + {1 \over {8!}} = {x \over {10!}}\), then x is equal to
  • A
    100
    Correct
  • B
    none of these .
  • C
    90
  • D
    170
14
The number of ways in which 9 different balls can be packed into 5 boxes, 4 of them containing 2 each and fifth only 1, is
  • A
    945
    Correct
  • B
    15120
  • C
    999
  • D
    22680
15
he number of ways in which 5 “ + “ and 5 “ – “ signs can be arranged in a line such that no two “ – “ signs occur together is
  • A
    P(5,5)
  • B
    none of these
  • C
    P(6,5)
  • D
    C(6,5)
    Correct