• Club Math is the first ever student math club at Kaua‘i Community College. The club is interested in the practicality and usefulness of mathematics in everyday living. The goal is to involve the community by promoting this ideal. What
• Club Math is the first ever student math club at Kaua‘i Community College. The club is interested in the practicality and usefulness of mathematics in everyday living. The goal is to involve the community by promoting this ideal. What follows is the last math puzzle printed two weeks ago followed by the answer. The club submits weekly brainteasers for the education page.
Going to Grandma’s:
You are on your way to visit your Grandma, who lives at the end of the valley. It’s her birthday, and you want to give her the cakes you’ve made.
Between your house and her house, you have to cross seven bridges, and as it goes in the land of make believe, there is a troll under every bridge. Each troll, quite rightly, insists that you pay a troll toll. Before you can cross their bridge, you have to give them half of the cakes you are carrying, but as they are kind trolls, they each give you back a single cake.
How many cakes do you have to leave home with to make sure that you arrive at Grandma’s with exactly two cakes?
Soution:
The trick is to make you think that you need a lot of cakes to start out with. In fact, it doesn’t matter how many bridges you have to cross, but you must have only two cakes to start out with. If you start out with the two cakes, the first troll will take half and then you’ll be left with only one cake. Since he is nice, he returns a single cake, bringing you back up to two cakes. The process is repeated over every bridge until you reach Grandma’s house. So the answer is two cakes
Next week’s teaser:
Hats:
There are two red hats and thee blue hats.
Three blindfolded men each take a hat and put it on. The first person takes off the blindfold and looks at the others’ hats. He can’t tell what color hat he is wearing. Then the second man takes off his blindfold and looks at the others’ hats. He is also unable to tell what color hat he has. Because of this, when the third man takes off his blindfold, he knows what color hat he is wearing.
What color hat is he wearing?
