Discussion
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- Question
If A1, A2, A3, A4, ..... A10 are speakers for a meeting and A1 always speaks after, A2 then the number of ways they can speak in the meeting is
Options- A. 9!
- B. 9!/2
- C. 10!
- D. 10!/2
- Correct Answer
- 10!/2
ExplanationAs A1 speaks always after A2, they can speak only in 1st to 9th places and
A2 can speak in 2nd to 10 the places only when A1 speaks in 1st place
A2 can speak in 9 places the remaining
A3, A4, A5,...A10 has no restriction. So, they can speak in 9.8! ways. i.e
when A2 speaks in the first place, the number of ways they can speak is 9.8!.
When A2 speaks in second place, the number of ways they can speak is 8.8!.
When A2 speaks in third place, the number of ways they can speak is 7.8!. When A2 speaks in the ninth place, the number of ways they can speak is 1.8!
Therefore,Total Number of ways they can speak = (9+8+7+6+5+4+3+2+1) 8! = = 10!/2
- 1. Out of 6 green ball, 4 blue ball, in how many ways we selectone or more balls ?
Options- A. 42
- B. 34
- C. 31
- D. 22 Discuss
- 2. A box contains 2 blue balls, 3 green balls and 4 yellow balls. In how many ways can 3 balls be drawn from the box, if at least one green ball is to be included in the draw?
Options- A. 48
- B. 24
- C. 64
- D. 32 Discuss
- 3. In how many ways the word 'SCOOTY' can be arranged such that 'S' and 'Y' are always at two ends?
Options- A. 720
- B. 360
- C. 120
- D. 24 Discuss
- 4. The number of sequences in which 4 players can sing a song, so that the youngest player may not be the last is ?
Options- A. 2580
- B. 3687
- C. 4320
- D. 5460 Discuss
- 5. In how many different ways could couples be picked from 6 men and 9 women ?
Options- A. 26
- B. 54
- C. 52
- D. 28 Discuss
- 6. In How many ways can the letters of the word 'CAPITAL' be arranged in such a way that all the vowels always come together?
Options- A. 360
- B. 720
- C. 120
- D. 840 Discuss
- 7. How many arrangements of the letters of the word ?BENGALI? can be made if the vowels are never together.
Options- A. 120
- B. 640
- C. 720
- D. 540 Discuss
- 8. There are 5 novels and 4 biographies. In how many ways can 4 novels and 2 biographies can be arranged on a shelf ?
Options- A. 26100
- B. 21600
- C. 24000
- D. 36000 Discuss
- 9. How many different words can be made using the letters of the word ' HALLUCINATION ' if all constants are together?
Options- A. 129780
- B. 1587600
- C. 35600
- D. None of these Discuss
- 10. If a+b+c = 21, what is the total number of non - negative integral solutions?
Options- A. 123
- B. 253
- C. 321
- D. 231 Discuss
Permutation and Combination problems
Search Results
Correct Answer: 34
Explanation:
7 × 5 = 35
35 ? 1 = 34
Correct Answer: 64
Explanation:
Total number of balls = 2 + 3 + 4 = 9
Total number of ways 3 balls can be drawn from 9 = 9C3
No green ball is drawn = 9 - 3 = 6 = 6C3
Required number of ways if atleast one green ball is to be included = Total number of ways - No green ball is drawn
= 9C3 - 6C3
= 9x8x7/3x2 - 6x5x4/3x2
= 84 - 20
= 64 ways.
Correct Answer: 24
Explanation:
Given word is SCOOTY
ATQ,
Except S & Y number of letters are 4(C 2O's T)
Hence, required number of arrangements = 4!/2! x 2! = 4!
= 4 x 3 x 2
= 24 ways.
Correct Answer: 4320
Explanation:
Let 'Y' be the youngest player.
The last song can be sung by any of the remaining 3 players. The first 3 players can sing the song in (3!) ways.
The required number of ways = 3(3!) = 4320.
Correct Answer: 54
Explanation:
Number of mens = 8
Number of womens = 5
Different ways could couples be picked = = 9 x 6 = 54 ways.
Correct Answer: 360
Explanation:
CAPITAL = 7
Vowels = 3 (A, I, A)
Consonants = (C, P, T, L)
5 letters which can be arranged in
Vowels A,I =
No.of arrangements = 5! x =360
Correct Answer: 720
Explanation:
There are 7 letters in the word ?Bengali of these 3 are vowels and 4 consonants.
Considering vowels a, e, i as one letter, we can arrange 4+1 letters in 5! ways in each of which vowels are together. These 3 vowels can be arranged among themselves in 3! ways.
Total number of words = 5! x 3!= 120 x 6 = 720
Correct Answer: 21600
Explanation:
4 novels can be selected out of 5 in
ways.
2 biographies can be selected out of 4 in
ways.
Number of ways of arranging novels and biographies =
= 30
After selecting any 6 books (4 novels and 2 biographies) in one of the 30 ways, they can be arranged on the shelf in 6! = 720 ways.
By the Counting Principle, the total number of arrangements = 30 x 720 = 21600
Correct Answer: 1587600
Explanation:
H L C N T A U I O
L N A I
There are total 131 letters out of which 7 are consonants and 6 are vowels. Also ther are 2L's , 2N's, 2A's and 2I's.
If all the consonants are together then the numberof arrangements = x 1/2! .
But the 7 consonants can be arranged themselves in x 1/2! ways.
Hence the required number of ways = = 1587600
Correct Answer: 253
Explanation:
Number of non - negative integral solutions = = 253
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