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Combinations MATHS - Combinations

Rajasthan Board (RBSE) - STD 11 Science - MATHS (Rajasthan - English Medium). 109 questions in this chapter.

Question types

Combinations question types

109 questions across 5 question groups — pick any mix to generate a MATHS paper with step-by-step answer keys.

109
Questions
5
Question groups
5
Question types
Sample Questions

Combinations questions

One sample from each question group in this chapter. Select any group above to see the full set with answer keys.

Q 1M.C.Q (1 Marks)1 Mark
If ${^\text{20}}\text{C}_{\text{r}}={^\text{20}}\text{C}_{\text{r+4}}$ is then ${^\text{r}}\text{C}_{\text{3}}$ equal to:
  • A
    54
  • ✓
    56
  • C
    58
  • D
    none of these.

Answer: B.

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Q 2M.C.Q (1 Marks)1 Mark
The value of $({^\text{7}}\text{C}_{\text{0}}+{^\text{7}}\text{C}_{\text{1}})+({^\text{7}}\text{C}_{\text{1}}+{^\text{7}}\text{C}_{\text{3}})+.....+({^\text{7}}\text{C}_{\text{6}}+{^\text{7}}\text{C}_{\text{7}})$ is:
  • A
    $2^{7}-1$
  • ✓
    $2^{8}-2$
  • C
    $2^{8}-1$
  • D
    $2^{8}$

Answer: B.

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Q 3M.C.Q (1 Marks)1 Mark
Three persons enter a railway compartment. If there are $5$ seats vacant, in how many ways can they take these seats?
  • ✓
    $60$
  • B
    $20$
  • C
    $15$
  • D
    $125$

Answer: A.

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Q 5M.C.Q (1 Marks)1 Mark
If ${^\text{20}}\text{C}_{\text{r}}={^\text{20}}\text{C}_{\text{r-10}}$ is then ${^\text{18}}\text{C}_{\text{r}}$ equal to:
  • A
    4896
  • ✓
    816
  • C
    1632
  • D
    None of these.

Answer: B.

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Q 132 Marks Questions2 Marks
There are $10$ persons named $P_1, P_2, P_3, ...., P_{10}.$ Out of 10 persons, 5 persons are to be arranged in a line such that in each arrangement $P_1$  must occur whereas $P_4$ and $P_5$ do not occur. Find the number of such possible arrangements.
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Q 225 Marks Questions5 Marks
In a village, there are $87$ families of which $52$ families have at most $2$ children. In a rural development programme, $20$ families are to be helped chosen for assistance of which at least $18$ families must have at most $2$ children. In how many ways can the choice be made?
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Q 255 Marks Questions5 Marks
How many different selections of $4$ books can be made from $10$ different books, if
  1. There is no restriction.
  2. Two particular books are always selected.
  3. Two particular books are never selected?
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