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February 20th, 2018 (Permalink)

The Puzzle of the Five Suspects

Who shot Victor Timm? The only witness to the shooting saw a short blond running away.

There are five suspects who each had the means, motive, and opportunity to commit the crime: Avery, Bailey, Casey, Davey, and Eddy.

Three of the suspects are short―less than six feet tall―and two are tall―greater than six feet. Three of the suspects have brown hair, while two have blond. At least one of the suspects is a tall blond.

Avery and Casey are the same height, whereas Davey and Eddy are different heights―that is, one is short and the other is tall. Bailey and Eddy have the same hair color, while Casey and Davey have different colors.

Which of the five suspects shot Timm?


February 1st, 2018 (Permalink)

What's New?

I have a new email course called "Logic Basics: Understanding Arguments"*, which consists of ten short lessons delivered daily by a company called Highbrow. It's a very brief introduction to the fundamental concepts of logic needed to analyze and evaluate reasoning―and, I might add, to understand fallacies.

The course is an extensive revision, especially in the later lessons, of a series posted here many years ago. Moreover, the last few lessons includes new material not covered in those posts. It's a Premium course, which means it's not free, but you can try out Highbrow's Premium service for a month for free, and the course only takes ten days! Check it out.

* Gary Curtis, Logic Basics: Understanding Arguments, Highbrow

Solution to the Puzzle of the Five Suspects: Avery and Casey are the same height, so either both are short or both are tall. However, either Davey or Eddy is tall, so if Avery and Casey were both tall then there would be three tall suspects. But we know that there are only two tall suspects. Therefore, Avery and Casey must both be short.

Since three of the other suspects are short, this means that Bailey must be tall. Moreover, the witness saw a short person running away, so we can eliminate Bailey as a suspect, which leaves four.

Casey and Davey have different hair colors, while Bailey and Eddy are either both brown-haired or both blond. If Bailey and Eddy were both blonds, then there would be three blond suspects, whereas we know that there are only two. Therefore, Bailey and Eddy both have brown hair, eliminating Eddy as a suspect and leaving three.

Since Bailey, Eddy, and either Casey or Davey have brown hair, this means that Avery must have blond hair. We also know that the other blond suspect is tall, which rules out Casey, who is short. Therefore, Casey must have brown hair and can be eliminated as a suspect. Three down and two to go.

So, Davey must be the tall blond suspect, but the shooter was described as a short blond. Davey is out, leaving one final suspect, who is the only one to fit the description of the fleeing shooter: Avery, a short blond.

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