Mental Floss 189

The answer to last week’s challenge is, Q: You’re rummaging around your great grandmother’s attic when you find five short chains each made of four gold links. It occurs to you that if you combined them all into one big loop of 20 links, you’d have an incredible necklace. So you bring it into a jeweller, who tells you the cost of making the necklace will be $10 for each gold link that she has to break and then reseal. How much will it cost?

A:  The most straightforward approach would be to break a link on the end of each of the five chains, and then reattach the link to the back of the next chain in the loop. This would cost you $50 for the five links that were broken and resealed. But you can actually do it for $40! Instead of breaking a link in each chain, break all four links in one of the chains and then use those four links to attach the remaining four chains together. Now you’ve saved $10.

This week’s challenge is:

Q: Adam and Eve play rock-paper-scissors 10 times. You know that: Adam uses rock three times, scissors six times, and paper once. Eve uses rock twice, scissors four times, and paper four times. There are no ties in all 10 games. The order of games is unknown. Who wins? By how much?

The answer along with a new challenge, next week.

Have an excellent weekend and don’t forget the upcoming International Conference on Thinking which is being held in Melbourne this year!

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