In each issue of the Automation Notebook we feature a section of brainteasers. These are the brainteaser answers from Issue 17, 2010 of the Automation Notebook. The brainteaser questions are repeated in black. The answers to the brainteaser questions are highlighted in red with explanations. You can view the brainteasers from Issue 17, 2010 without the answers here:

1. Top cat? Top dog?

The combined weight of the factory’s resident dog and cat is 27 lbs. The dog’s weight is an odd number, yet the cat’s is even. If his weight is twice that of hers, what do each of them weigh?

Answer: The male cat weighs 18 lbs and the female dog weighs 9 lbs.

2. Bookworm

The AutomationDirect Catalog has gotten thicker each time we’ve printed it. Volume 10 was approximately 1.5″ thick (including the cover) and the volumes have increased in size an average of 1/4″ each issue. If the volumes were arranged on the shelf as shown below, and a bookworm started at the first page of volume 10 and ate his way straight to the last page of volume 13, how far would he have traveled? You can assume that the thickness of the covers is 1/16″ for all the catalogs.

Answer: Given the way that the books are arranged on the shelf, the distance from the first page of volume 10 to the last page of vol. 13, includes only the front cover of vol.10, plus the entire thickness of volumes 11 and 12, and only the rear cover of Vol 13.  This works out to 1/16”, plus 1.75”, plus 2.0”, plus 1/16”, or 3 7/8 inches (or 3.875” if he is a decimal oriented bookworm). 

3. Three Color Techs

Three technicians: Mr. Black, Mr. Blue, and Mr. Red were wiring a control panel, and each was using only a single color of wire: one black, one blue, and one red.

“Have you noticed that none of us is using the color of wire that corresponds to our own name?” asked the man using the red wire.

“You’re absolutely right!” replied Mr. Blue

What color of wire was each man using? 

Answer: The extra clue here is that Mr. Blue is not using red wire, as he responds to the question asked by the tech who is using the red wire. Since he can’t be using blue wire either, we know that Mr. Blue must be using Black wire.  Mr. Black therefore must be wiring with Red wire. And that leaves Blue wire for Mr. Red.