A completely black dog was strolling down main street during a total blackout affecting the entire town. Not a single streetlight had been on for hours. As the dog crosses the center of the road a Buick Skylark with two broken headlights speeds towards it, but manages to swerve out of the way just in time. How could the driver see the dog to swerve in time?
As I went through the garden gap,
Who should I meet but Dick Red-cap!
A stick in his hand, a stone in his throat,
If you’ll tell me this riddle, I’ll give you a groat.
(Said to be the lyrics to A Cherry)
I slipped down a slippery gap,
Found a man with a red cap,
He had a stick in his back and a stone in his belly,
Riddle me this and I’ll give you a penny.
You are given eight coins and told that one of them is counterfeit. The counterfeit one is slightly heavier than the other seven. Otherwise, the coins look identical. Using a simple balance scale, how can you determine which coin is counterfeit using the scale only twice?
First weigh three coins against three others. If the weights are equal, weigh the remaining two against each other. The heavier one is the counterfeit. If one of the groups of three is heavier, weigh two of those coins against each other. If one is heavier, it’s the counterfeit. If they’re equal weight, the third coin is the counterfeit.