Re: Maths Doubt

Posted by Gayyam on May 07, 2014; 2:29am
URL: http://discussion-forum.276.s1.nabble.com/Maths-Doubt-tp7588767p7588769.html

The sequence of length 5 is to be composed of only 0's and 1's. Consider the cases depending on how many 0's comprise the sequence, and the number of possible sequences with at least 2 consecutive zeroes for each case-
0 0's - 0 sequences
1 0's - 0 sequences
2 0's - 4 sequences
3 0's - 10 sequences
4 0's - 5 sequences
5 0's - 1 sequence.

Thus, there are 20 such sequences. And I too got the same answer as you did. However, if we are forced to accept 19 as the correct answer, then one possible explanation is to not include the 5 0's case as that doesn't have any 1; assuming the sequences have to have both 0's and 1's.