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AMAZING BRAIN TEASERS - Series Two; for active minds to Exercise their senses and have fun


Question 1
There are three light switches outside a room. Inside is a single light bulb, controlled by one of the three switches. You need to determine which switch operates the bulb. You can turn the switches on and off as many times as you wish (they are all off to begin with), but may only enter the room once. There is no one there to help you. The door to the room is closed, and there are no windows, so you cannot see inside. How can you discover which switch operates the bulb?


  View answer

Do the following: 1. Turn ON two switches, and leave one OFF. 2. Wait a few minutes. 3. Turn one switch from ON to OFF. One is now ON and two are OFF 4. Enter the room. - If the light is ON, it is controlled by the switch you left ON. - If the light bulb is OFF, touch it. If it is warm it is controlled by the switch you turned ON and OFF. If it is cold, it is controlled by the switch you never turned on.

 

Question 2
You have two ropes. Each rope takes one hour to burn. These ropes are not identical, nor are they uniform; i.e. it does not necessarily take half an hour for half the rope to burn (if you have trouble visualizing this, imagine a rope of varying thickness across its length). With only these two ropes and a way to light them, how do you measure out 45 minutes?

View answer

Light both ends of one rope, and only one end of the other rope. This will cause the first rope to burn out in 30 minutes. When the first rope burns out, there will be 30 minutes left on the second rope. So then, light the other end of the second rope, and the rest of it will burn out in 15 minutes. 30 + 15 = 45 minutes.
Question  3
You are playing a game of dodge ball with two other people, John and Tom. You're standing in a triangle and you all take turns throwing at one of the others of your choosing until there is only one person remaining. You have a 30 percent chance of hitting someone you aim at, John has a 50 percent chance, and Tom a 100 percent change (he never misses). If you hit somebody they are out and no longer get a turn. If the order of throwing is you, John, then Tom; what should you do to have the best chance of winning?


View answer

Miss the first time on purpose. If you try to hit John and do. Then Tom goes next and he will hit you and you will lose for sure. If you aim at Tom and hit him then John will go for you. If you miss on your first turn John will go for Tom for sure because he is a stronger player. If he hits him then it's just you and John, but you are going first. If he misses him then Tom will hit John and it will be just you and Tom, but again in this case you are going first.
Question  4
A wealthy wise old woman feared that her daughter was lazy and as a result rather stupid. When the old woman died, her will stipulated that her assets were to be liquidated and a check was to be written for the full amount. The check was to be placed in one of three envelopes. The other two envelopes would contain a blank piece of paper. If the daughter could determine from the writing on the envelope which envelope contained the check, she would inherit her mother's fortune. Otherwise, the fortune would go to the old woman's favorite charity for animals. The daughter was not allowed to touch the envelopes. Her decision had to be made based on the writing on the envelopes. The daughter was told that only one envelope had a true statement and that the other two statements were false. The envelopes had the following writing: 1. This envelope does not have the check 2. This envelope has the check 3. The second envelope does not have the check Which envelope should the daughter pick?


View answer

The daughter should pick envelope 1. Unfortunately she picked envelope 3. Statements 1 and 2 were false, and the only true statement was statement 3. If the check was in envelope 1, that would make statement 1 false, statement 2 false and statement 3 is the only true statement. If the check was in envelope 2, statements 1 and 2 would both be true. If the check was in envelope 3, statements 1 and 3 would both be true.
Question  5
Many many years ago, I got married to a widow who was pretty as could be. This widow had a grown-up daughter with whom my father fell in love, soon the two were wed. This made my dad my son-in-law, for my daughter was my mother being my father's wife. I soon became the father of a baby boy. My little baby then became a brother-in-law to dad. And so became my uncle. For if he was my uncle, then that also made him brother to the widow's grown-up daughter ,who of course, was my step-mother. Father's wife then had a son, who kept them on the run. And he became my grandson, for he was my daughter's son. Who is my grandpa?


View answer

I am my own grandpa [My wife's my mother's mother(i.e.grandma)which makes me her grand child,My grandpa is married her; and that is me;her husband]
Question  6
A man is on the run from the police, after stealing large gold bars. He has 3 gold bars in his arms - each weighing 10kg each. The problem is, as he runs from the police, he must cross a mile long, fragile bridge which can only support 100kg. The man weighs 80kg. How could he transport all 3 gold bars?


View answer

He should Juggle them; and only a maximum of 2 bars will be with him at any point and time to act on the bridge leaving the third one in the air. This makes only a maximum of 100kg total to act on the bridge
Question  7
Tim and Joy are long distance lovers. Tim has just purchased an engagement ring for Joy and wants to mail it to her. Unfortunately the only way to ensure the ring will be received is to place a lock on the package. Tim has locks and Joy has locks but neither have keys for each others' locks. How can they ensure the ring isn't stolen?


View answer

Tim places a lock on the package and sends it to Joy. Joy places a lock on it as well and sends it back to Tim.Tim opens his lock and then sends it back to Joy
Question  8
Usain and Mo race one another over 100m. When Usain crosses the finish line, Mo is only at the 90m mark. They agree to have a second race, but to make it fairer, Usain will begin 10m behind the starting line. All things being equal, who would you expect to win the race?


View answer

Usain will win. Both will reach the 90m at the same time and with his faster running speed Usain will cover the last 10m faster
Question 9
There is a chain nailed to the wall. The chain is 10 feet long and the centre of the chain dips down 5 feet from where each side of the chain is nailed to the wall. How far are the 2 ends of chain from each other?


View answer

The ends are touching. In order for the chain to dip down 5 feet (exactly half) the ends must be touching and the chain is effectively folded in half.
Question 10
How can the number four be half of five?


View answer

FIVE. Take away the F and E and you're left with IV. That's four in Roman Numerals
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