Posted by **Sam** on Monday, October 26, 2009 at 4:40pm.

At the faculty costume party, each teacher from Transylvania Middle School came dressed as his or her favorite creepy creature. The teachers arrived one at a time, and when a new teacher came in, each of the teachers alredy there lined up at the door and shook hands with the newcomer. Count Dracula (Mr. Balb, the math teacher) kept track of the number of handshakes exchanged. He said that there were 171 handshakes exchanged at the party. How many teachers came to the costume party

- math -
**Reiny**, Monday, October 26, 2009 at 4:48pm
Let the number of teachers be n

the number of handshakes of n people is

C(n,2)

so C(n,2) = 171

n!/(2!(n-2)!) = 171

n(n-1) = 342

n^2 - n - 342) = 0

(n-19)(n+18) = 0

n = 19 or n= -18, but n > 0

So 19 teachers came

- math -
**Alexis**, Thursday, October 23, 2014 at 10:19pm
People -19

Handshakes- 18

Total handshakes- 171

## Answer This Question

## Related Questions

- math - At the faculty costume party , each teacher from Transylvania Middle ...
- 7th grade Math - At a faculty costume party, each teacher from transylvania ...
- 8th grade - At a faculty costume party, each teacher from transylvania Middle ...
- English - 1. He went to the teachers' room. There were many teachers, and he was...
- Math - A school has four art teachers, three music teachers, and eight history ...
- 7th grade math (probability) - I'm not sure how to answer this: 3. THe 7th grade...
- Probability - A school has 8 math teachers, 6 English teachers, and 2 geography ...
- algebra - Lincoln High School has 98 teachers. Of the 42 female teachers 8 teach...
- algebra 2 - Lincoln High School has 98 teachers. Of the 42 female teachers, 8 ...
- AE.. is this right - In any given multicultural classroom, what are the concerns...

More Related Questions