Tom, Mary and Jill have apartments in the same building. A security system for their building costs $750. Tom is willing to pay $100 for the security system, Mary is willing to pay $300 and Jill is willing to pay $300. They have a meeting to vote on whether to pay $250 each for the security system. At least two of them must vote for the system to be installed before the vote is passed. The efficient outcome is to have the security system installed. After the meeting the security system will __________, which illustrates ___________.