How dumb are you? (Riddle) - Page 11

doormat · #**101** 08-22-2007, 01:09 PM

[ QUOTE ]
You have 9 jars containing an infinite number of marbles of identical size. All the jars contain marbles weighing 1 gram, except one jar has marbles weighing 1.1 grams. You have a scale and are allowed ONE measurement. How can you figure out which jar contains the marbles weighing 1.1 grams?

[/ QUOTE ]

Put the following on the scale: 1 marble from jar 1, 2 from jar 2, 3 from jar 3, etc.

If the weight comes out to be 4.4 or 9.9, you know that jar 4 or 9 respectively is the correct jar, etc.

doormat

doormat · #**102** 08-22-2007, 01:12 PM

OK, here's one for you:

You have 50 quarters on the table in front of you. You are blindfolded and cannot discern whether a coin is heads up or tails up by feeling it. You are told that x coins are heads up, where 0 < x < 50. You are asked to separate the coins into two piles in such a way that the number of heads up coins in both piles is the same at the end. You may flip any coin over as many times as you want. How will you do it?

FishSticks · #**103** 08-22-2007, 01:24 PM

Do you know what x is? Or is x a random unknown?

You could always cheese it and stand them on their sides snicker.

theblitz · #**104** 08-22-2007, 01:26 PM

You split them into 2 separate piles. One pile has x coins and the other has 50-x.
You then turn over all the coins in the pile that has the most coins.

So, for example, if there are 20 heads then the smaller pile will have 20 coins of which z will be heads. So, the number of heads in the other pile will be 30-z. Thus the number of tails there will be z.
When you flip the coins there will now be z heads in the large pile too.

theblitz · #**105** 08-22-2007, 01:31 PM

My turn:
You have 4 light bulbs in a room.
You are outside but cannot see into the room.
There are 4 light switches - one per light.
You are allowed to enter the room ONCE only.
How do you identify which light goes with which switch?

Bostaevski · #**106** 08-22-2007, 01:33 PM

I agree with doormat

doormat · #**107** 08-22-2007, 01:35 PM

[ QUOTE ]
You split them into 2 separate piles. One pile has x coins and the other has 50-x.
You then turn over all the coins in the pile that has the most coins.

So, for example, if there are 20 heads then the smaller pile will have 20 coins of which z will be heads. So, the number of heads in the other pile will be 30-z. Thus the number of tails there will be z.
When you flip the coins there will now be z heads in the large pile too.

[/ QUOTE ]

Sorry, this does not work. By your own example, if I tell you there are 20 heads and you make two piles of 20 and 30, maybe there will be eight heads in the small pile and 12 in the large pile. Flipping over all of the large pile would leave you with 30-12 = 18 heads, which does not match the 8 heads in the small pile.

doormat · #**108** 08-22-2007, 01:41 PM

[ QUOTE ]
You have 4 light bulbs in a room.
You are outside but cannot see into the room.
There are 4 light switches - one per light.
You are allowed to enter the room ONCE only.
How do you identify which light goes with which switch?

[/ QUOTE ]

You could leave switch one off, switch two on for a long time then turn off, switch three on for a short time then turn off, and leave switch 4 on.

When you walk in the room, the one that is burning is switch 4, the cool bulb goes with switch one, the warm bulb with switch three and the hot one with switch two.

doormat

Bostaevski · #**109** 08-22-2007, 01:43 PM

[ QUOTE ]
OK, here's one for you:

You have 50 quarters on the table in front of you. You are blindfolded and cannot discern whether a coin is heads up or tails up by feeling it. You are told that x coins are heads up, where 0 < x < 50. You are asked to separate the coins into two piles in such a way that the number of heads up coins in both piles is the same at the end. You may flip any coin over as many times as you want. How will you do it?

[/ QUOTE ]

OMFG I think I got this one
1) Flip every coin over. Now there are 50-x heads
2) Separate into two piles of coins
a. Pile#1 has x coins
b. Pile#2 has 50-x coins
3) Flip every coin in pile#2 back over.

theblitz · #**110** 08-22-2007, 01:45 PM

[ QUOTE ]
[ QUOTE ]
You have 4 light bulbs in a room.
You are outside but cannot see into the room.
There are 4 light switches - one per light.
You are allowed to enter the room ONCE only.
How do you identify which light goes with which switch?

[/ QUOTE ]

You could leave switch one off, switch two on for a long time then turn off, switch three on for a short time then turn off, and leave switch 4 on.

When you walk in the room, the one that is burning is switch 4, the cool bulb goes with switch one, the warm bulb with switch three and the hot one with switch two.

doormat

[/ QUOTE ]
You are close but being on for a long time and being on for a medium time are not disernable.