P and S can be in following ways
P****S******
*P****S*****
**P****S****
.
.
.
7 ways and P S has permutation in 2 ways
so total 14 ways
other 10 letters with 2 Ts...total 10!/2!
so ans 14*10!/2!
In how many wayscan the letters of the word PERMUTATIONS be arranged if there are always 4 letters between P and S ?
possible positions are 1,6 ... 2,7 ... 3,8 ... 4,9 ... 5,10 ... 6,11 .... 7,12
So there are 14 Permutations of arrangements of P and S..
Now. no of words = 14*10!/2!
P and S can be in following ways
P****S******
*P****S*****
**P****S****
.
.
.
7 ways and P S has permutation in 2 ways
so total 14 ways
other 10 letters with 2 Ts...total 10!/2!
so ans 14*10!/2!
asish...u posted while i was typing....hehe
u type so fast!!!!