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In how many ways can a person invites his 2 or more than 2 friends out of 5 friends for dinner?

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To solve the problem of how many ways a person can invite 2 or more friends out of 5 friends for dinner, we can follow these steps: ### Step 1: Identify the total number of friends The total number of friends available is 5. ### Step 2: Determine the combinations needed We need to find the number of ways to invite 2, 3, 4, or all 5 friends. This means we will calculate the combinations for each of these cases. ### Step 3: Use the combination formula The combination formula is given by: \[ nCr = \frac{n!}{r!(n-r)!} \] where \( n \) is the total number of items to choose from, \( r \) is the number of items to choose, and \( ! \) denotes factorial. ### Step 4: Calculate the combinations for each case 1. **Inviting 2 friends**: \[ \text{Number of ways} = 5C2 = \frac{5!}{2!(5-2)!} = \frac{5 \times 4}{2 \times 1} = 10 \] 2. **Inviting 3 friends**: \[ \text{Number of ways} = 5C3 = \frac{5!}{3!(5-3)!} = \frac{5 \times 4}{2 \times 1} = 10 \] 3. **Inviting 4 friends**: \[ \text{Number of ways} = 5C4 = \frac{5!}{4!(5-4)!} = 5 \] 4. **Inviting all 5 friends**: \[ \text{Number of ways} = 5C5 = \frac{5!}{5!(5-5)!} = 1 \] ### Step 5: Sum the combinations Now, we add all the combinations calculated: \[ 10 \text{ (for 2 friends)} + 10 \text{ (for 3 friends)} + 5 \text{ (for 4 friends)} + 1 \text{ (for 5 friends)} = 26 \] ### Final Answer Thus, the total number of ways a person can invite 2 or more friends out of 5 friends for dinner is **26**. ---
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NAGEEN PRAKASHAN ENGLISH-PERMUTATION AND COMBINATION -Exercise F
  1. If .^(16)C(r) = .^(16)C(r+6), then find .^(5)C(r).

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  2. Determine n if (i) ^2n C2:^n C2=12 :1 (ii) ^2n C3:^n C3=11 :1

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  3. Determine n if (i) .^(2n) C2: "^n C2=12 :1 (ii) .^(2n) C3: "^n C...

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  4. Determine n if (i) ^2n C2:^n C2=12 :1 (ii) ^2n C3:^n C3=11 :1

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  5. If .^(15)C(r): .^(15)C(r-1) = 1:5, then find r.

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  6. If .^(n-1)P3 :^(n+1)P3 = 5 : 12, find n.

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  7. If .^(n)P(r) = 720 and .^(n)C(r) = 120, then find r. .

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  8. If .^(n+1)C(r+1.): ^nCr: ^(n-1)C(r-1)=11:6:3 find the values of n and ...

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  9. If ""^(n)C(4),""^(n)C(5) and ""^(n)C(6) are in A.P. then the value of ...

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  10. If alpha=\ \ ^m C2,\ then find the value of \ ^(alpha)C2dot

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  11. In how many ways can a team of 11 players be selected from 14 players?

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  12. In how many ways 2 persons can be selected from 4 persons?

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  13. In how many ways can a person invites his 2 or more than 2 friends out...

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  14. In how many ways can 11 players be selected from 14 players if (i) a...

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  15. In how many ways can 5 subjects be chosen from 9 subjects if three sub...

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  16. In how many ways can 4 books be chosen from 12 books if (i) there is...

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  17. A bag contains 5 black and 6 red balls. Determine the number of way...

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  18. In 25 cricket players, there are 10 batsmen, 9 bowlers, 4 all-rounders...

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  19. There are 8 math's books and 6 science books in a almirah. In how many...

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  20. There are 3 parts A,B and C in a question paper of Math's, which inclu...

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