Use Your Grey Cells

Puzzles 1. The Puzzle: You have 9 balls, equally big, equally heavy - except for one, which is a little heavier. How would you identify the heavier ball if you could use a pair of balance scales only twice? 2. The Puzzle: One of twelve pool balls is a bit lighter or heavier (you do not know) than the others. At least how many times do you have to use an old balance-type pair of scales to identify this ball? 3. The Puzzle: You have eight bags, each of them containing 48 coins. Five of these bags contain only true coins, the rest of them contain fake coins. Fake coins weigh 1 gram less than the real coins. You do not know what bags have fake coins and what bags have real coins. You can use a scale with precision up to 1 gram. Making only one weighing and using the minimum number of coins, how can you find the bags containing the fake coins? 4. The Puzzle: Real jelly babies have a mass of 10 grams, while imitation jelly babies have a mass of 9 grams. Spike has 7 cartons of jelly babies, 4 of which contain real jelly babies, the others imitation. Using a scale only once (and minimum disturbace of the boxes contents!), how can Spike determine which cartons contain real jelly babies?

5. 6. The Puzzle: You need tohaving boil eggs forbowls, exactly 9 minutes, or else the visiting The Puzzle: Imagine three with the following capacities: Duchess will complain, and you will lose your job as head chef. In bowl A (8 liters capacity) are 5 liters of water. But have 2 Hourglasses, measures 7-minute, and the other Inyou bowl B (5only liters capacity) are one 3 liters of water. measures 4-minutes. How can you correctly measure 9 minutes? In bowl C (3 liters capacity) are 2 liters of water. Can you measure exactly 1 liter, pouring only 2 times?

7. The Puzzle: In front of you are several long fuses. You know they burn for exactly one hour after you light them at one end. The entire fuse does not necessarily burn at a constant speed. For example, it might take five minutes to burn through half the fuse and fifty-five minutes to burn the other half.

With your lighter and using these fuses, how can you measure exactly threequarters of an hour of time? 8. The Puzzle: What 5-digit number has the following features? If we put the numeral 1 at the beginning, we get a number three times smaller than if we put the numeral 1 at the end of the number. 9. The Puzzle: Mrs Goodsworthy has 6 gorgeous hats. 3 are green, 2 are blue, and 1 is canary yellow. Four of her friends, Janet, Collette, Melanie, and Judith have come for tea and are trying on her hats. Mrs. Goodsworthy helps each friend put on a hat and has them stand in a line as shown below. None of the ladies can see what color hat she is wearing. Janet can see the colors of the hats Collette, Melanie, and Judith are wearing. Collette can see the colors of the hats Melanie and Judith are wearing. Melanie can see the color of the hat that Judith is wearing. Judith cannot see the color of any of the hats. Mrs. Goodsworthy asks her friends what color hat each of them is wearing, and Janet says she can't tell. Collette says she isn't able to tell either, and Melanie says she can't tell. Judith, on the other hand, is able to announce the color of her hat. How Judith was able to figure out the color of her hat, and what was the color? 10. The Puzzle: You are about to leave for holiday, but you forgot socks! You race back to your room, but all the lights are off, so you can't see the color of the socks. Never mind, because you remember that in your drawer there are ten pairs of white socks, ten pairs of black socks, and eleven pairs of blue socks, but they are all mixed up. How many of your socks do you need to take before you can be sure to have at last one matching pair?