If X and Y are 2 finite sets such that n() = 9, n( XY) - 4 and n( XY) -15, then n() is
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Answer:
Step-by-step explanation:
The word "LAMEFIREALARM" word consists of
2L , 2M, 2E , 2R , 3A , F and I
no of words with the above letters such that M's are not together
=Total No of words- M's are together
Total no of words
When M's are together . considering 2 M's as one
therefore there are
No of ways
(b)No of ways such that M's are separated by at least 2 letters
at least 2 letter means 2 letter, 3 letter ......11 letters
So we have to subtract no of ways where there are 1 letter in between M's from total no of ways where 2 M's are not next to each other
No of ways in which there is 1 letter between 2 M's
This can be done by considering 11 cases
In first case Place first M in Starting Position and 2 M on third place
Second case place First M in 2 nd Position and second M on 4 th place
Similarly For 11th case
Place first M in 11th place and second M on 13th place
Total ways
So , the total number of arrangements of the letters of the word LAMEFIREALARM where the two M's are separated by atleast two letters is