Amazon Interview Question: If in a room there are 10 per... | Glassdoor.co.in

# If in a room there are 10 persons and if each person has to

shake hands with all other then total how many hand shakes will be there

27

10C2=45

Anonymous on 02-May-2013
2

should be 90

Tank on 20-Jun-2013
0

Forgot 90 Milk Shakes

tank on 20-Jun-2013
6

10(10-1)/2

Anonymous on 30-Nov-2013
2

"Each other" leaves this very open-ended; that depends on if A shakes with B or A shakes with B &amp; C, OR if A shakes with all the other nine, etc. I would say the answer would have to be one of two: 10 or 100. If each person chooses only one to shake with, it would be ten. IF each person shakes with everyone there, all ten, it would be 100.
Since this question is pretty vague, Some people may come to the conclusion that the answer is Either 90 assuming everybody stayed to shake hands with each other meaning the first person shook hands with 9 people and the 2nd person did the same etc etc bringing it to the conclusion that you got 90 handshakes.

Another answer towards for people would be 45 being that the first person gave a hand shake to 9 people and then left and then the 2nd person gave a handshake to 8 people n then left etc and etc making it 9+8+7+6+5+4+3+2+1=45.

Case 1: 90, Case 2: 45 on 15-Sep-2014
4

simply formulas:
n*(n-1)/2
(n-1)*(n/2)

J on 04-Oct-2014
0

Lock in 90 thanks

Anonymous on 19-Oct-2014
3

45

G B on 26-May-2015
0

5

Anonymous on 21-Jul-2015
1

n(n-1)/2 = 10(10-1)/2 = 45
If there are 10 persons, the first shakes hands nine times, the second eight times (already shook with first person), and so on. In other words, 9+8+7+6+5+4...

Slomoshn on 10-Aug-2015
2

1. n(n-1)/2
2. 10*9/2
3 90/2
4. 45

Anonymous on 19-Sep-2015
0

If you say 90 you are including the repetetions. If first person shakes 9 times, the next one requires only 8 shakes. So it goes like, 9, 8 ,7 ,6...1. Can use the formula n*(n-1)/2/. So we get only 45 shake hands. It is similar to no of squares in the chess board. There squares will apply.

Anonymous on 22-Sep-2015
1

9

Anonymous on 02-Oct-2015
0

45

Anonymous on 25-Feb-2016
0

If one person is lefty?

Anonymous on 04-Mar-2019