### #1 - Weighing Balance Puzzle

You can place weights on both side of weighing balance and you need to measure all weights between 1 and 1000. For example if you have weights 1 and 3,now you can measure 1,3 and 4 like earlier case, and also you can measure 2,by placing 3 on one side and 1 on the side which contain the substance to be weighed. So question again is how many minimum weights and of what denominations you need to measure all weights from 1kg to 1000kg.

For this answer is 3^0, 3^1, 3^2... That is 1,3,9,27,81,243 and 729.

### #2 - Water Pails Puzzle

If you had an infinite supply of water and a 5 quart and 3 quart pails, how would you measure exactly 4 quarts? and What is the least number of steps you need?

1. Fill 5 quarter pill ( 5p - 5, 3p - 0)
2. Transfer to 3 quart pail (5p - 2, 3p - 3)
3. Empty 3 quarter pill ( 5p - 2, 3p - 0)
4. Transfer 2q from 5 pail to 3 pail (5p - 0, 3p - 2)
5. Fill 5 quarter pail(5p - 5, 3p - 2)
6. Transfer 1q from 5 pail to 3 pail(5p - 4, 3p - 3)

### #3 - IQ PUZZLE

You have two strings whose only known property is that when you light one end of either string it takes exactly one hour to burn. The rate at which the strings will burn is completely random and each string is different.

How do you measure 45 minutes?

Light both the ends of the first string and one end of the second string. 30 minutes will have passed when the first string is fully burned, which means 30 minutes have burned off the second string. Light the end of the second string and when it is fully burned, 45 minutes will have passed.

### #4 - Half Full Or Half Empty Riddle

There is a barrel with no lid and some wine in it. 'This barrel of wine is more than half full,' said Curly. 'No it's not,' says Mo. 'It's less than half full.' Without any measuring implements and without removing any wine from the barrel, how can they easily determine who is correct?

Tilt the barrel until the wine barely touches the lip of the barrel. If the bottom of the barrel is visible then it is less than half full. If the barrel bottom is still completly coverd by the wine, then it is more than half full.

### #5 - Hour Glass Puzzle

I have two sand hour glasses:
1. A 7 minute one and
2. An 11 minute one.

Using just these 2 sand hour glasses, how can i measure time as 15 minutes ?

1. Start both the 7 minute hour glass & 11 minute hour glass.
2. Wait till the 7 minute hour glass times out. Time is 7 minute!
3. Restart the 7 minute hour glass. At this time 11 minute hour glass will have 4 minutes left to time out.
4. As soon as 11 minute glass times out invert the 7 minute hour glass. Total time now is 11 minutes.
5. After inverting 7 minute hour glass, it will now have 4 minutes left for time out.
6. After these 4 minutes times out, the total time is 15 minutes.

### #6 - Hourglass Time Puzzle

There are 2 sand hourglasses.
The small one can measure 5 hours and the large one can measure 7 hours.

How can we measure 16 hours with 2 sand hourglasses running together ?

Steps:
* Start both sand hourglasses at the same time.
* You flip over the small sand hourglass when it finishes the first 5 hours.
* Flip over the large one when it finishes its first 7 hours.
* When the small sand hourglass runs to 10 hours, flip over the small and large sand hourglass at the same time. It means the large sand hourglass will run 3 hours again. When the large sand hourglass run to 13 hours (7 + 3 + 3), flip both the small and large sand hourglass over again to run another 3 hours.

### #7 - Hour Glass Riddle

You have two hour glasses one measure 7 minutes and other measure 4 minutes.
Using these two hour glasses, you need to measure exactly 9 minutes.

How come ?

Step1 : Start running both the hourglasses.
Step2 : when 4 minutes hourglass runs out, turn it over.
Step2 : when 7 minutes hourglass runs out, turn it over.
Step2 : Again when 4 minutes hourglass runs out, turn 7 minute hourglass over (it was running for exactly one minute.)
Step2 : 8 minute already passed and allow one minute of 7 hour glass to get over. ==>9 minute

### #8 - Simple Simple Google Interview Puzzle

The puzzle is if the shopkeeper can only place the weights in one side of the common balance. For example if shopkeeper has weights 1 and 3 then he can measure 1, 3 and 4 only. Now the question is how many minimum weights and names the weights you will need to measure all weights from 1 to 1000. This is a fairly simple problem and very easy to prove also.  Answer for this puzzle is given below.

This is simply the numbers 2^0,2^1,2^2 ... that is 1,2,4,8,16... So for making 1000 kg we need up to 1, 2, 4, 8, 16, 32, 64, 128, and 512

### #9 - Easy Gallon Riddle

I have a five and a three gallon jar.

Assuming there us an infinite supply of water , how can i measure one gallon water ?

-> Fill up the 3 gallon jar first , Pour it into the five gallon jar.
-> Fill up the 3 gallon jar again, and fill up the rest of the 5 gallon jar,
=> and you should have 1 gallon left over in the 3 gallon jar.

### #10 - Gallon Riddle

There are three gallons X,Y & Z.

Gallon X having capacity of eight liters is with filled with 5 liters of liquid.
Gallon Y having capacity of five liters is with filled with 3 liters of liquid.
Gallon Z having capacity of three liters is with filled with 2 liters of liquid.

How can you measure 1 liter of liquid in minimum number of steps ?

Step 1) Pour 1 litre of liquid from gallon X to gallon Z. Now 4 litres of liquid is left in the gallon X and gallon Z is full.

Step 2) Pour liquid from gallon Z to gallon Y. Now as soon as gallon Y is full , you know there is one liter of liquid is in gallon Z.