• 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.
The missing dollar:
If a mile long train travels through a mile long tunnel going at 15 miles per hour, how long will it take to go through the tunnel?
Solution:
Speed = Distance/Time.
So, Time = Distance/Speed
Take the distance you have to travel, divide it by the speed, and you will have your answer.
The only thing is that, to make it completely through the tunnel, the train has to travel two miles, not one. Assume the train enters the tunnel and travels a mile. At this point, just the nose of the train emerges from the tunnel. As the train is a mile long, it needs to travel another mile for its tail to emerge from the tunnel.
2 miles = 2/15 hour or .133333333 hours or 8 minutes 15 mph
2 miles X 60 minutes = 8 minutes = 8 minutes 15 miles/hour X 1 hour 1
Next week’s teaser:
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?