A Hand Shake
Calculus
Level
2
There are some people in a room in and they give everyone a handshake.
Here’s the only rule: 1. They only give handshakes to people that they haven’t given yet. how many people are there in the room?
There are 15 handshakes in total.
5
15
10
6
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1 solution
Let there be n people in the room.
As a fact we know that one handshake requires two hands (every 60 seconds in Africa,a minute passes?)
So combination of n people handshaking only once[ C 2 n ]= ( n − 2 ! ) ( 2 ! ) n ! =15
Where n!=n (n-1) (n-2) ....... (1)
= > ( n − 2 ) ! ∗ 2 ! ( n ) ∗ ( n − 1 ) ∗ ( n − 2 ) ! = 1 5
= > n ∗ ( n − 1 ) = 3 0
= > n = 6
Boom!