Saturday, November 28, 2009

Commutations 1

The Acme Plumbing Company will send a team of 3 plumbers to work on a certain job. The company has 4 experienced plumbers and 4 trainees. If a team consists of 1 experienced plumber and and 2 trainees, how many different such teams are possible?

This question is an example of a problem that you will need your nCr button on your calculator to solve. First of all, the company can choose 1 experienced plumber out of 4. That's 4 take 1 (4 nCr1), or 4. The company can choose 2 trainees out of 4. That's 4 take 2 (4nCr2), or 6.
Since there are two different types of plumber, you have two different spots to place these numbers: _ times (multiplied by)_. Using blanks and mulitplying is key to commutations.
6 times 4 is 24, the answer.
Posted by at

1 comment:

  1. Hans Georg LundahlJanuary 23, 2010 at 11:56 AM

    Before Nicea Gospel Canons differred, most having four take four, some having any four take three, some having any four take two and some even having any four take one.

    How many different Gospel Canons were possible for a diocese, including big ones (like Rome) that had four?

    ReplyDelete

Subscribe to: Post Comments (Atom)