Irwin Publishing, Inc., as part of its summer sales meeting, has arranged a golf outing at the Quail Creek Golf and Fish Club. Twenty people have signed up to play in the outing. The PGA Professional...

Irwin Publishing, Inc., as part of its summer sales meeting, has arranged a golf outing at the Quail Creek Golf and Fish Club. Twenty people have signed up to play in the outing. The PGA Professional at Quail Creek is responsible for arranging the foursomes (four golfers playing together). How many different foursomes are possible?