Em Holliday

Problem

You have a 5 litre and a 3 litre jug, you need exactly 4 litres. How will you get it? You have as much water as you need.

Answer 1

Fill the 5 litres, use that to fill the 3 litre jug, leaving 2 litres in the large jug. Tip out the 3 litre jug. Now pour the remaining 2 litres into the 3 litres jug. Refill the 5 litre and use it to top up the 3 litre jug, using one litre. You are left with 4 litres in the large jug.

Answer 2

Fill the 5 litre jug, then use that to fill the 3 litre jug, leaving 2 litres in the large jug. Tip out the 3 litre jug and put the remaining 2 litres inanother container (or your pocket). Now repeat leaving the 2 litres in the large jug and return the first 2 litres to the large jug, giving you 4 litres.

Picture from: http://www.crystalpurewateraz.com/images/PouringWater.jpg

Problem    

You have 8 billard balls which all look identical. One is defective and weighs slightly more than the other balls. You cannot notice the difference by weighing them in your hands.

You also have a balance scale one which you can weigh the balls twice only. How can you work out which is the heavy ball?

Answer (Don't look til you tried working it out first!)

Weigh six balls, three per side. If these are the same weight then the heavy ball is one of the two you didn't weigh, weigh those two and you'll find the heavy ball. If one of the groups of three balls is heavier then the defective ball is in that group. Now weigh two of the three balls. If you defective ball is on the scale it will be heavier, if the scale balance then the defective ball is the one not on the scales.

Picture from: http://discover.edventures.com/images/termlib/b/balance_scale/support.gif

Problem

You Have a chessboard (8 x 8 squares, black and white).

1. How many squares can you find with sides 2 x 2?

2. Complete this pattern: Length of side : No. of squares; 1:64, 2:?, 3:?, 4:?, 5:?, 6:?, 7:?, 8:?.

3. What is the total number of squares on a chessboard?

4. How many oblongs/rectangles are there? (One side longer than the other)

Answers

1. 49

2. 1:64, 2:49, 3:36, 4:25, 5:16, 6:9, 7:4, 8:1.

3. 204

4. 1120 (Don't forget oblongs/rectangles can be 1x2, 1x3, 1x4...2x3, 2x4, 2x5....3x4, 3x5...etc.)

Problem from Brainwave: HBJ Teacher Resource Books. Pg 12.

Picture from:http://www.sjgames.com/proteus/img/chessboard.jpg

Problem

How can you cut a cake into eight pieces with just three perfectly straight cuts?

Answer

Two cuts into quarters vertically (top to bottom) then one cut horizontally through the cake to get 8. (like a sponge cake)

Picture from: http://i5.photobucket.com/albums/y187/vsamperuru/v-chocTruffleCake1.jpg

Problem

You have two hourglasses. One empties in 7 minutes, the other empties in 4 minutes. How can you use these two hourglasses to measure exactly 9 minutes?

Answer

???

Picture from: http://www.lacrossemccormick.com/products/hourglass/hourglass.jpg

Problem

You have a large container filled with Jelly Beans. There are only three colours - red, green and yellow. You are blindfolded. How many jelly beans do you need to draw out of the container to guarantee you get two jelly beans of the same colour?

Answer

Four.

Picture from: http://www.kiddyhouse.com/Songs/alpha/jellybeans.gif

Problem

A sneaky coin trader offers you nine coins. They appear identical but one if fake and slightly lighter than the others. Using the balance, how can you isolate the fake coin in just two weighings?

Answer

???

Picture from:mhttp://www.fotosearch.com/comp/CRT/CRT151/15322-27IL.jpg

Problem

Two agents (people), one tells the truth and one always lies. There are two exits from the room, one leads you safely home and the other leads you to certain death. You don't know which agent tells the truth, which lies and you don't know which door to take to get home. You may ask only one question to find out which is the exit, both agents will give you an answer. What is the question you will ask?

Answer

???

Problem

There are three lights inside a room at the end of a long hall. The switches are at the other end of the hall. The lights are off. You may manipulate the switches and walk down to the room only once. How can you work out which switch controls each light?

Answer

Switch on the first switch and leave it on for ten minutes. Then turn that switch off, turn on the second switch and go down to the room. If the light is on, the second switch works it, if the light is off but the globe is warm the first switch works this light, if the globe is off and cool then the third switch works the light.

Smartiepants answer

Go down and open the door first so you can see into the room!