Logic riddles for teens

interviewlogicmath

Four people need to cross a rickety bridge at night. Unfortunately, they have only one torch and the bridge is too dangerous to cross without one. The bridge is only strong enough to support two people at a time. Not all people take the same time to cross the bridge. Times for each person: 1 min, 2 mins, 7 mins and 10 mins. What is the shortest time needed for all four of them to cross the bridge?
It is 17 mins. 1 and 2 go first, then 1 comes back. Then 7 and 10 go and 2 comes back. Then 1 and 2 go again, it makes a total of 17 minutes.
73.40 %
72 votes
logicclever

A sign on the barber's door says "I shave only those who do not shave themselves." Does the barber shave himself?
There is no answer, it's a paradox. It cannot be made to work. Search: "Barber paradox"
73.31 %
49 votes
logicclean

An archeologist claims he found a Roman coin dated 46 B.C. in Egypt. How much should Louvre Museum pay for the coin? Note: Roman coins can really be found in Egypt
Nothing. That coin is as phony as a three dollar bill. In 46 B.C., they wouldn't have known how many years before Christ it was.
73.31 %
85 votes
cleantrickycleverlogic

There are ten people in a house. Everybody wants to make a hand shake with only people shorter than themselves. Assume everybody is different in height. How many hand shakes are made?
0, because a taller person wants to shake hands with a shorter person. But the shorter person doesn't want to shake hands with him.
73.25 %
76 votes
cleansimplelogic

Mr. and Mrs. Mustard have six daughters and each daughter has one brother. How many people are in the Mustard family?
There are nine Mustards in the family. Since each daughter shares the same brother, there are six girls, one boy and Mr. and Mrs. Mustard.
73.24 %
406 votes