How can I solve this problem and what strategy do I use?

Question

1. A telephone company engineer needs to install phone lines for a political convention meeting. Private lines are to connect 5 committee chairpersons’ desks with each other. How many lines will need to be installed? _______

Strategy used? _______________________________________

Answer 1

Person 1 is connected to 4 others

Person 2 is connected to 3 other

Person 3 is connected to 2 other

Person 4 is connected to 1 other person 5

Answer 2

Well suppose there were 2 people. How many lines would you need. 1.

AB

If there were 3 people. call them A, B, C

AB AC BC 3 lines

4 people A B C D

AB AC AD

BC BD

CD

6 lines

What happens if we add one more person ?