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Thinking Thursdays – Riddles and Brainteasers

It’s time again for our Riddles and Brainteasers post for the month. Last month’s post really got your brain working out. Hopefully, today’s questions have you testing your mental agility again! As usual, we will post the 10 riddles below, then the answers, with a graphic separating the two, so hopefully you will notice if you start to scroll too far (but I won’t tell anyone if you cheat and peek at the answers!)

Don’t forget to tell us in the comments how you did!

The Questions

  1. When John was six years old, he hammered a nail into his favorite tree to mark his height. Ten years later at age sixteen, John returned to see how much higher the nail was. If the tree grew by five centimeters each year, how much higher would the nail be?
  2. I am four times as old as my daughter. In 20 years time I shall be twice as old as her. How old are we now?
  3. There is a lily pad in a small pond. The lily pad doubles in size each day. On the 20th day, it covers the whole pond. On what day was the lily pad  half the size of the pond?
  4. Which word is the odd one out?
    Seventy Brawl
    Clover Proper
    Carrot Swing
    Change Travel
    Sacred Stone
  5. You want to boil a two-minute egg. If you only have a three-minute timer (hourglass), a four-minute timer and a five-minute timer, how can you boil the egg for exactly two minutes?
  6. What has five wheels, though most people think of it as having only four. You cannot use it without that one wheel more, you can put things in it, you can strap things on top, You can’t find it in the market, but you can still go shop. What is it?
  7. If you were to spell out every whole number (in English), how high would you have to count before you would use the letter A?
  8. There is a certain club which is for men only. There are 600 men who belong to this club and 5% of these men wear one earring. Of the other 95% membership, half wear two earrings and the other half wear none. How many earrings are being worn in this club?
  9. A 300 ft. train is traveling 300 ft. per minute must travel through a 300 ft. long tunnel.  How long will it take the train to travel through the tunnel?
  10. You are standing in front of a room with one lightbulb inside of it. You cannot see if it is on or off. Outside the room, there are 3 switches in the off positions. You are allowed to flip whatever switches you want but can only enter the room once. How can you determine which switch controls the lightbulb?


The Answers

  1. The nail would be at the same height since trees grow at their tops.
  2. I am 40 and my daughter is 10. (In twenty years, I will be 60 and she will be 30)
  3. Day 19.  Most will say day 10, but that is incorrect because on day 20 the lily pad will have  doubled from day 19, so 19 must be half the size of the pond.
  4. Carrot. When the first and last letters are removed from the other words, they still spell another word.
    Seventy -> Event Brawl -> Raw
    Clover -> Love Proper -> Rope
    Swing -> Win Change -> Hang
    Travel -> Rave Sacred -> Acre
    Stone -> Ton
  5. Once the water is boiling, turn the three-minute timer and five-minute timer over. When the three-minute timer runs out, put the egg in the boiling water. When the five-minute timer runs out, two minutes have elapsed, and it is time take the egg out of the water. You don’t need the four-minute timer for this riddle.
  6. A car
  7. One thousand
  8. Six hundred. We know that 5%, or 30 of the men are wearing one earring. Of the other 95%, or 570, we know that half are wearing two earrings and the other half none. This is the same as if they all wore one.
  9. 2 minutes. The front of the train will make it through the tunnel in one minute, but the back of the train will just be entering the tunnel. It takes another minute for the back of the train to exit the tunnel.
  10. You turn 2 switches “on” and leave 1 switch “off” and wait about a minute. Just before you enter the room, turn one switch from “on” to “off”. Once in the room, if the lightbulb is on, it is obviously the switch that is still “on”. If the lightbulb is cold, then it was the switch that you never touched. If the lightbulb is off, but warm to the touch, it must be the last switch you turned off right before you entered the room.

How well did you do with our riddles today? Make sure you let us know in the comments!

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