Standing in a line..I M TALLER....:D

no one trying???????????

no one tried dis?cum on atleast giv sum suggestions.............

this is a david morin problem !!!!!

Well i can take 3 cases here.

Case 1: everyone is standing in decreasing order of heights.

Here the first person is the tallest, but he cannot see anyone in front of him, so he wont say ' i am taller than everyone in front of me'. Then the next person onwards cannot say the same, because the people in front of him are taller than him. So in this case the answer is 0.

Case 2: everyone is standing in increasing order of heights.

Here there are N people, so the first person wont say that 'i am taller than everyone in front of me' but from the next person onwards, everyone can say that they are the tallest. Hence, the answer in this case is N-1.

Case 3: mixed arrangement of tall and short people.

Now, when the tallest person among that group comes somewhere in the line, the people behind him cannot say that they are taller. The number of ways in which the tall person can be placed in the line is N+1.

When the tallest person is standing in the front of the line, 0 people say that they are taller.
When the tallest person is standing at position 2 in the line, 0 people say that they are taller (since the first person cannot compare his height with anyone)
From the third position onwards till the N+1^th position of the tallest person, 2 to N people can say that they are taller. And the tallest person, of course, can say that he is the tallest.

Hence the average number of people who can say that they are taller is :

2+ 3+ 4....N+1N +1

I dont know if my answer is correct. It might be wrong, but plz do give me the solution to it. [1]

check this- it will help

http://www.physics.harvard.edu/academics/undergrad/probweek/sol82.pdf