Aptitude - Permutation and Combination - Discussion
Discussion Forum : Permutation and Combination - General Questions (Q.No. 12)
12.
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?
Answer: Option
Explanation:
'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. |
Discussion:
68 comments Page 7 of 7.
Nandu said:
1 decade ago
@Santosh.
If you see "SELECT" then use "ncr" and if you see "ARRANGE" use npr.
No confusion.
If you see "SELECT" then use "ncr" and if you see "ARRANGE" use npr.
No confusion.
Ankur said:
1 decade ago
It should be done in simple way i.e. 10 c4 = 210 ways then 4 letters can be written in 4! i.e 24 therefore 210*24 = 5040.
Onkar said:
1 decade ago
We can't use permutation here because they have mentioned that no repetition is permissible and in 4 number word only possible solution is 210. 10C4 = 210.
Haribabu said:
1 decade ago
Why are you taking 10c4 so many ways like 10c2, 10c5?
If I take total 10 letters, so I calculate 10! = (10*9*8*7*6*5*4*3*2*1).
So please explain clearly.
If I take total 10 letters, so I calculate 10! = (10*9*8*7*6*5*4*3*2*1).
So please explain clearly.
Sanjana said:
10 years ago
Can the clear explanation of this problem can be given by someone? Since I dint get it.
Shareef said:
10 years ago
Why 4 is taken?
Sreeparna said:
10 years ago
Why permutation here?
Ankit raj boudh said:
10 years ago
Logarithms ===> total = 10 alphabets.
We have to form 4-letter words, without repeating the letters. We have place for 4 alphabets.
In 1st blank, out of 10, anyone of it can come, so we have 10 choices ---> 10.
In 2nd blank, now, 9 letters are left, out of 9 you can choose one ----> 10*9.
In 3rd blank, now 8 left, i.e. ---> 10*9*8.
In 4th blank, any remaining of 7 letters can come ---> 10*9*8*7 = 5040.
Here we are using --- Logarithms --- word which contain different alphabets.
If it contain one or two alphabets more then one time then above solution is applicable.
Solve this example in place of Logarithms use logarithm. Please solve this.
We have to form 4-letter words, without repeating the letters. We have place for 4 alphabets.
In 1st blank, out of 10, anyone of it can come, so we have 10 choices ---> 10.
In 2nd blank, now, 9 letters are left, out of 9 you can choose one ----> 10*9.
In 3rd blank, now 8 left, i.e. ---> 10*9*8.
In 4th blank, any remaining of 7 letters can come ---> 10*9*8*7 = 5040.
Here we are using --- Logarithms --- word which contain different alphabets.
If it contain one or two alphabets more then one time then above solution is applicable.
Solve this example in place of Logarithms use logarithm. Please solve this.
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