SOLUTION: A number of small towns set up their own telephone system. Between each pair of towns they stretched a main phone cable. In all, they put up 28 separate cables connecting all of

Question 212196: A number of small towns set up their own telephone system. Between each pair of towns they stretched a main phone cable. In all, they put up 28 separate cables connecting all of the towns. How many towns were there?
Answer by rapaljer(4671) (Show Source): You can put this solution on YOUR website!
This is a combination problem. Let x = number of towns.

Then, C(x,2) = 28. This will be

x=8 or x= -7

Reject the negative value of x, so x=8 towns!

R^2

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