Thread: Permutation of the letters ABCDEFGH

Can anyone please check my below answers!

Q.1 How many permutations of the letters ABCDEFGH contain

a) the strings CAB and BED?

myans.) 5P5 = 5! = 120 ways

b) the strings BCA and ABF?

myans.) permutation not possible since B cannot be followed by both C and F at the same time.

Thanks for any help!

Originally Posted by robocop_911

Can anyone please check my below answers!

Q.1 How many permutations of the letters ABCDEFGH contain

a) the strings CAB and BED?

myans.) 5P5 = 5! = 120 ways

b) the strings BCA and ABF?

myans.) permutation not possible since B cannot be followed by both C and F at the same time.

Thanks for any help!

Well, the letters CAB can appear in 6 positions...

CABxxxxx, xCABxxxx, xxCABxxx, xxxCABxx, xxxxCABx and xxxxxCAB

BED cannot appear in the last 2 positions, so there are only 4 positions that permit CAB and BED.

Of these, the remaining letters have 3! permutations each...

So there are 4*6 = 24 permutations allowing the combination CABED.

Originally Posted by robocop_911

Can anyone please check my below answers!

Q.1 How many permutations of the letters ABCDEFGH contain

a) the strings CAB and BED?

myans.) 5P5 = 5! = 120 ways

b) the strings BCA and ABF?

myans.) permutation not possible since B cannot be followed by both C and F at the same time.

Thanks for any help!

I take my word back!

Originally Posted by sean.1986

Well, the letters CAB can appear in 6 positions...

CABxxxxx, xCABxxxx, xxCABxxx, xxxCABxx, xxxxCABx and xxxxxCAB

BED cannot appear in the last 2 positions, so there are only 4 positions that permit CAB and BED.

Of these, the remaining letters have 3! permutations each...

So there are 4*6 = 24 permutations allowing the combination CABED.

Can anyone please verify whether whatever "sean1986" has said is Correct or Not! Thanks!

Hello, robocop_911!

Q.1 How many permutations of the letters ABCDEFGH contain

a) the strings CAB and BED?

my answer: . ways . . . . not quite

The permutation must contain .

Then we have four objects to permute: .

And there are: . ways.

b) the strings BCA and ABF?

my answer: .The permutation not possible
since B cannot be followed by both C and F at the same time.

I agree!