Logical Thinking Puzzles

These classic logic problems range from fairly easy to very difficult, but think of them as mental weightlifting--as you get stronger, you can lift more.
The use of math and logical deduction will provide the key to these problems. I will post these often--one puzzle at a time. If you're the first to solve it correctly, you'll earn extra credit. Leave a comment with your solution. I will reward the first correct answer with a dollop of extra points


I believe Ms Livvy scored the win on #5, but the refs are checking the video tape. . . . yes, it's official! She scores a smidgeon of extra credit.

Here's a new one for you Ms RaeRal:

6. logic pie:

How is it possible to cut a traditional circular cake into 8 equal size pieces, with only 3 cuts?

Two correct answers were submitted, using different methods (see comments posted), which just goes to show that there's more than one right answer. Ms Ralston's correct response beat Ms Samantha T's by a mere 1 hour, 4 minutes. If only Sam T's had delayed dinner, she would have been our winner. So a tbs of extra points for Rae Ral.


Send in those logic droppings!






1. American Idol

American Idol auditioned four performers for their television show. None, of course, were musicians, but can you figure each guy's day job, his age (19,20,21,22) and home town based on the following facts?

Gordon is two years younger or older than the guy from Cleveland who is a truck driver.

Either Deke or the guy from Seattle (who may or may not be Paul) delivers pizzas.

The guy from New York is younger than Dex but older than the one who is a carpenter.

The 22 year old from San Francisco isn't the one who is a waiter.



Congrats to Mr. Wennerholm, first correct response (below) to puzzle #1. He wins a dollop of extra points! Miss Childs responded a minute later, but, alas, was mistaken on one count. Here's another for the logicians out there--easier?


2. TRUE STATEMENTS

A. The number of false statements here is one.

B. The number of false statements here is two.

C. The number of false statements here is three.

D. The number of false statements here is four.

Which of the above statements is true?

(You must explain your reasoning to win)


Too easy! Miss Isa wins without opposition. She earns a pinch of extra credit! Look for more puzzles soon.

#3 CARD LOGIC

Three playing cards lying face up, side by side. A five is just to the right of a two. A five is just to the left of a two. A spade isjust to the left of a club, and a spade is just to the right of a spade. What are the three cards?


Many winners for puzzle #3, but first with the facts are Miss Childs & company. An iota of extra credit for them. Other correct answers were submitted by Mr. Wennerholm, Mr. Gillette, and Miss Ralston.


#4 Knights and Knaves

A very special island is inhabited only by knights and knaves. Knights always tell the truth, and knaves always lie.
You meet five inhabitants: Rex, Peggy, Sue, Joe and Homer. Rex tells you, `Sue could claim that I am a knave.' Peggy tells you that only a knave would say that Joe is a knave. Sue claims that Homer is a knave. Joe tells you that neither Rex nor Sue are knaves. Homer says that either Peggy is a knight or Rex is a knight.

Can you determine who is a knight and who is a knave.

(note: I don't have the solution yet to this problem. Contestants will need to provide a logical explanation with their answer.)

What a monster! Mr. Gillette outstrips all competition on Puzzle #4: Knights and Knaves. I don't think the dude even broke a sweat! He earns a peck of extra credit.


Here's another for the logicians out there.

Logic Puzzle #5 Join the Military Today!

Earlier this year five young people decided they wanted to join a military service. Who signed up to which service in which month and how old are they?

Ages: 16, 17, 18, 19, 20

Months: March, April, May, June, July

How the person signed up to join the SAS is a mystery; was this Geoff?
The 18 year old signed up 3 months before the 19 year old.
Alice is 2 years younger than the person who signed up to the navy.
Brian signed up 2 months after the girl who signed up to the army.
Jill signed up 2 months after the 16 year old (not Alec) who signed up a month after Alice.
Brian signed up the month after the person who signed up to the marines.
The person who signed up to the marines signed up 2 months after Alec.
Brian, who is not 20, is older than Alec.
The 19 year old signed up 1 month before the person that signed up to the SAS.
Did Alice join the Air force?