Hey rosala, your link doesn't need the " /new " at the end...it should just be
https://web2.0calc.com/questions/permutations-and-combinations-lt-3
error error I saw an answer for this, but it has been deleted....maybe because it was incorrect,,, sorry
1.Find the no. of permutations of letters a , b , c , d, e , f , g taken all at a time if neither “beg” nor “cad” patterns appear in any word.
Permuatations of 7 letters =7! =5,040
The word "beg" appears in 7 - 3 + 1 = 5 positions
The remaining 4 letters permute in 4! =24 ways
5 x 24 = 120 pemutations
Similarly, the word"cad" appears in 7 -3 + 1=5 positions
The remaining 4 letters permute in 4! = 24 ways
5 x 24 = 120 permutations.
The combinations of the word "beg" and "cad" as one word "begcad" appears in 7 - 6 + 1 =2 positions only. Similarly, the word "cadbeg" also appears in 2 positions only for a total of 4 words. Each one of these words is excluded twice, once when it is included in the 120 permuations of "beg" and once in the permutations of the word "cad". So these 4 words should be added back to the total.
So, the total permuations left should be =5,040 -120 - 120 + 4 =4,804 permutations.
Melody: You are pretty good at this kind of problem, so, please take a look at it.
Hi Rosala,
I have anwered on the original thread :)
https://web2.0calc.com/questions/permutations-and-combinations-lt-3#r9