Arithmatical - Permutations and Combinations
DIRECTIONS : Problems based on Permutations.
1. |
In how many different ways can the letters of the word ‘JUDGE’ be arranged in such a way that the vowels always come together? |
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A. 48 |
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B. 120 |
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C. 124 |
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D. 160 |
Solution |
The word JUDGE has 5 different letters. |
When, the vowels UE are always together, they can be supposed to form one letter. |
Then, we have to arrange the letters JDG(UE). |
Now, 4 letters can be arranged in 4! = 24 ways. |
The vowels (UE) can be arranged in 2!= 2 ways. |
Required number of ways | = (24 x 2) |
= 48. |
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2. |
How many 4 letter words with or without meaning, can be formed out of the letters of the word, 'LOGARITHMS', if repetition of letters is not allowed? |
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A. 40 |
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B. 400 |
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C. 5040 |
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D. 2520 |
Solution |
'LOGARITHMS' contains 10 different letters. |
Required number of words | = Number of arrangements of 10 letters, taking 4 at a time. |
‹=› 10p4 |
‹=›(10 x 9 x 8 x 7) |
‹=› 5040. |
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3. |
In how many ways a committee, consisting of 5 men and 6 women can be formed from 8 men and 10 women? |
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A. 266 |
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B. 5040 |
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C. 11760 |
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D. 86400 |
Solution |
Required number of ways |
‹=› (8C5 ×10C6) |
‹=›(8C3 ×10C4) |
=(8x7x6/3x2x1 ×10x9x8x7/4x3x2x1) |
‹=›11760 |
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4. |
In how many ways can the letters of the word 'LEADER' be arranged? |
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A. 72 |
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B. 144 |
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C. 360 |
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D. 720 |
Solution |
The word 'LEADER' contains 6 letters namely 1L , 2 E, 1A,1D, and 1R. |
Required number of ways | = 6! / (1!) (2!) (1!) (2!) |
= 360. |
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5. |
How many words can be formed by using all letters of the word 'BIHAR'? |
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A. 60 |
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B. 120 |
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C. 150 |
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D. 180 |
Solution |
The word 'BIHAR' contains 5 different letters. |
Required number of words | = 5P5 |
= 5! |
= (5 x 4x 3 x 2 x 1) |
= 120. |
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