Thnx
Find the total no. of ways in which 6 "+" and 4 "-" signs can be arranged in a line such that no 2 -ve signs occur together.
Ans : 7C4 = 35
Why is it not : 6! x 7P4
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4 Answers
virang1 Jhaveri
·2009-09-23 01:40:31
I think so they considered each + to be different which is wrong
Lokesh Verma
·2009-09-23 01:45:01
the answer is correct
no of ways to arrange 6 + signs in a row is 1... because all + signs are teh same
now you have to insert 4 - signs in 7 gaps...
hence 7C4
RAY
·2009-09-23 03:14:50
yes...right:)...,,,,,,abheek since + are all same and - are all same so
(6! x 7P4) /(6! x 4!) which is same as the answer