Question

in how many ways can a ser of five letters be selected from the english alphabets?

Answer 1

) No(22)

no. of ways of choosing 7 letters out of 24=24c7
no of ways of placing 7 letters w/o repitition=7!
no of ways of arranging 2 letters A and B= 2!
total no of ways=(24c7)*7!*2!

3 years agoHelpfull: Yes(25) No(10)

We can fix A and B in two ways with 7 letters in between them. Now 7 letters can be selected and arranged in between A and B in 24P7 ways. Now Consider these 9 letters as a string. So now we have 26 - 9 + 1 = 18 letters
These 18 letters are arranged in 18! ways. So Answer is 2 x 24P7 x 18!
Infact, 2 x 24P7 x 18! = 36 x 24!.

2 years agoHelpfull: Yes(18) No(1)

There are P(24,7) arrangements of the letters of the alphabet (excluding A and B)taken ten at a time, and hence 2*P(24,7) strings of 9 letters, each beginning and ending with an a and
b(either letter coming first in a string).
For each of these strings, there are 18 ! ways to arrange the 17 remaining letters and the string.
So there are altogether 2*P(24,7)*18 ! arrangements of the desired type.

3 years agoHelpfull: Yes(16) No(5)

ans will be 24!*2*18

4 years agoHelpfull: Yes(10) No(11)

24p7*2!*18!
2! because AB are interchangeable
24p7 to select 7 alphabets out of 24 alphabets
18! because we hace considered the 9 letters set as one letter and arranged rest of the letters
hence 24p7*2!*18!

3 years agoHelpfull: Yes(9) No(5)

24p7*2!
out of 24 we have to opt 7 letters(26-A&B)
and 2! for A&B

3 years agoHelpfull: Yes(6) No(3)

24c7 *7!*2!

4 years agoHelpfull: Yes(5) No(2)

Answer: 36 * 24! or 24P7 * 2 * 18!
Explanation:
We can fix A and B in two ways with 7 letters in between them. Now 7 letters can be selected and arranged in between A and B in 24P7 ways. Now Consider these 9 letters as a string. So now we have 26 - 9 + 1 = 18 letters
These 18 letters are arranged in 18! ways. So Answer is 2 x 24P7 x 18!
Infact, 2 x 24P7 x 18! = 36 x 24!. So go for Option B as it was given as OA.

2 years agoHelpfull: Yes(4) No(0)

total ways=22*21*20*19*18*17*16*15*14*2
2 ways for changing the position of A and B

4 years agoHelpfull: Yes(2) No(9)

ans is 2*sqrt(2)/3

4 years agoHelpfull: Yes(2) No(13)

24p7*2*18!

2 years agoHelpfull: Yes(2) No(2)

We can fix A and B in two ways with 7 letters in between them. Now 7 letters can be selected and arranged in between A and B in 24P7 ways. Now Consider these 9 letters as a string. So now we have 26 - 9 + 1 = 18 letters
These 18 letters are arranged in 18! ways. So Answer is 2 x 24P7 x 18!
Infact, 2 x 24P7 x 18! = 36 x 24!

2 years agoHelpfull: Yes(2) No(0)

Excluding A and B, there is a total of 24 letters in the alphabet. Out of that, 7 letters are to be selected and arranged between them. Thus to select and arrange 7 letters from 24 letters ==> 24P7 and so now we have arranged 9 letters including A and B. 
The remaining 17 letters can be arranged in 17! ways. 
But it is not necessary that A is in the 1st position followed by 7 letters and B is in the 9th position.B can be anywhere from the 9th position to the last 26th position like
A_ _ _ _ _ _ _ B _ _ _ _ _ _ upto 26th.... , _A _ _ _ _ _ _ _ B _ _ _ _ upto 26th...., and so on. Thus there are 18 ways to fill the letters A and B.

And finally it is also not necessary that A must be before those 7 letters and B after them. It can also be as B followed by those 7 letters followed by A.(B_ _ _ _ _ _ _A_ _....) . Thus there are two ways of arranging them.

To conclude the total number of ways is,
24P7 * 17! * 18 * 2!
==> 24! / (24-7)! * 17! * 36
Total ways = 24! * 36

1 year agoHelpfull: Yes(2) No(0)

A_ _ _ _ _ _ _ B

first place= 22
second plac=21
third=20
.
.
.
seventh=14
total ways= 22*21*20*19*18*17*16*15*14

4 years agoHelpfull: Yes(1) No(13)

2*18*24!

2 because a,b and b,a 
24! because except a and b other can select any place 
18 because group a-b can place in 24 by 18 ways

3 years agoHelpfull: Yes(1) No(3)

24c7*7!*2!

3 years agoHelpfull: Yes(1) No(1)

2 x 24P7 x 18!

2 years agoHelpfull: Yes(1) No(0)

24p7*2 ... is correct answer

2 years agoHelpfull: Yes(1) No(0)

24c7*7!*2*18!

2 years agoHelpfull: Yes(1) No(0)

can anyone give its proceedings..??

3 years agoHelpfull: Yes(0) No(1)

only gopal amreliya is correct .all other answers are wrong including first one

3 years agoHelpfull: Yes(0) No(1)

24*23*22*21*20*19*18

3 years agoHelpfull: Yes(0) No(0)

sorry forgot to mention about the a&b they also can interchange so..24c7*7!*18!*2!=36*24!

3 years agoHelpfull: Yes(0) No(0)

26 P 7=26!/19! 
there are 26 letters in English alphabet 
only 7 letters should be between A and B 
so it can be solved by using permutation.

2 years agoHelpfull: Yes(0) No(0)

This is not a question in "Blood Relation" topic !!!!!

2 years agoHelpfull: Yes(0) No(0)

A can be at 1st position and B can be at 9th position,A can be at 2nd position then B can be at 10th position and so on...
this can be arrange in 18 ways
a and b can be arrange in 2 ways 
and rest 24 alphabet can be arrange in 24!
so answer can be given as 2*18*24!