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A committee of 2 boys is to be selected ...

A committee of 2 boys is to be selected from 4 boys. In how many ways can this be done ?

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To solve the problem of selecting a committee of 2 boys from a group of 4 boys, we can use the concept of combinations. Here's the step-by-step solution: ### Step 1: Identify the values of N and R - **N** is the total number of boys, which is 4. - **R** is the number of boys to be selected, which is 2. ### Step 2: Use the combination formula The formula for combinations is given by: \[ ^nC_r = \frac{n!}{(n - r)! \cdot r!} \] In our case, we need to calculate \( ^4C_2 \). ### Step 3: Substitute the values into the formula Substituting \( N = 4 \) and \( R = 2 \) into the formula: \[ ^4C_2 = \frac{4!}{(4 - 2)! \cdot 2!} \] ### Step 4: Calculate the factorials Now, we need to calculate the factorials: - \( 4! = 4 \times 3 \times 2 \times 1 = 24 \) - \( (4 - 2)! = 2! = 2 \times 1 = 2 \) - \( 2! = 2 \times 1 = 2 \) ### Step 5: Substitute the factorial values back into the formula Now we can substitute these values back into our combination formula: \[ ^4C_2 = \frac{24}{2 \cdot 2} = \frac{24}{4} \] ### Step 6: Simplify the expression Now, simplify the expression: \[ ^4C_2 = 6 \] ### Conclusion Thus, the number of ways to select a committee of 2 boys from 4 boys is **6**. ---
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MODERN PUBLICATION-PERMUTATIONS AND COMBINATIONS -OBJECTIVE TYPE QUESTIONS (D) VERY SHORT ANSWER TYPE QUESTIONS
  1. Evaluate the following : (i) ""^(8)P(5) (ii) ""^(10)P(3) ...

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  2. Find 'r' when : (i) ""^(10)P(r )=2 ""^(9)P(r ) (ii) ""^(11)P(...

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  3. Find 'n' if 2 ""^(5)P(3)= ""^(n)P(4)

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  4. How many 3-digit even numbers can be formed from the digit 1,2,3,4,5,6...

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  5. How many 3 digit numbers are there, with distinct digits, with each ...

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  6. Find n if .^(n-)P(3): .^(n)P(4) = 1:9.

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  7. Four persons A, B, C and D are to the seated at a circular table. In h...

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  8. In how many ways can 6 beads of same colour form a neclace ?

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  9. If .^(2n)C(3):.^(n)C(3)=12:1, find n.

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  10. If ""^(n)C(8)= ""^(n)C(9), find the value of n.

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  11. If ""^(2n)C(1), ""^(2n)C(2) and ""^(2n)C(3) are in A.P., find n.

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  12. From a class of 32 students, 4 are to be chosen for a competition. In ...

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  13. The no. of ways can 5 sportsmen be selected from a group of 10 sportsm...

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  14. How many selection of 4 books can be made from 8 different books?

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  15. A committee of 2 boys is to be selected from 4 boys. In how many ways ...

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  16. Sudha wants to choose any 9 stamps from a set of 11 different stamps. ...

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  17. How many lines can be drawn through 6 points on a circle ?

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  18. How many triangles can be drawn through n points on a circle ?

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  19. A polygon has 44 diagonals , then the number of its sides is

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  20. In how many ways can 12 things be equally divided among 4 persons ?

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