SOLUTION: In a party 15 people shake their hands with each other. How many times did the hand-shake take place?
Algebra.Com
Question 776329: In a party 15 people shake their hands with each other. How many times did the hand-shake take place?
Answer by solver91311(24713) (Show Source): You can put this solution on YOUR website!
Pick one person as the "start". That person can shake hands with 14 different people. Pick the next person. That person can also shake hands with 14 different people, but you have already counted one of those 14 in the 14 that you counted for the "start" person, so only count 13 for person number 2. Then 12 for person number 3...and so on down to the second to the last person who can do 1 unique pairing. So, in sum, add the numbers from 1 to 14. 1 plus 14 is 15. 15 times 14 is 210. 210 divided by 2 is 105. So 105 different handshakes.
John
Egw to Beta kai to Sigma
My calculator said it, I believe it, that settles it
RELATED QUESTIONS
If 20 people in a class shake hands with each other exactly once, how many handshakes... (answered by Edwin McCravy)
A math team of 13 people all shake hands with each other exactly once. How many hand... (answered by solver91311)
1 - How many handshakes can take place if there are 100 people and no one shakes hands... (answered by khwang)
i have invited nine people to a party. They all shake hands with me, and each pair shake... (answered by ikleyn)
The 8 people at a party shook hands exactly once with each of the others before the 9th... (answered by AnlytcPhil,fractalier)
Seven matrons assembled for a meeting,shake hands with one another. How many handshakes... (answered by stanbon,richwmiller)
In a group of 20 people, how long will it take each person to shake hands with each of... (answered by jorel555)
ther were 20 people in the house each shake one another. how many hand shakes took... (answered by stanbon)
1. If two people shake hands, how many handshakes take place?
2. If three people shake... (answered by ewatrrr)
