Quote:
Originally Posted by murali13_84
hi i have following doubts pls some1 help me solve this with explanation
a) 1 red 3white and 2blck flags are arranged such that
1. no 2 adjacent flags are of same colour
2. the flags at the end shud b diff color
how many arrangements are posible
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see 3 W means all W can't be in middle ..
we can have
W_W_W_
or
_W_W_W
now 1st way..
3 blank places can be filled in 3 ways 3!/2!1! = 3 (bcoz 2 identical b and 1 r)
W
RW
BW
B W
BW
RW
B W
BW
BW
R
and in the second case
similarly again we have 3 cases
RW
BW
BW BW
RW
BW BW
BW
RW
so we have
6 different cases