How can you measure 9liter using 2 gallons of 12 liters and 5 liters?
8 Steps
Steps <------> 2L Gallon <-------> 5L Gallon
1<--------------->12<--------------->0
2<--------------->07<--------------->5
3<--------------->07<--------------->0
4<--------------->02<--------------->5
5<--------------->02<--------------->0
6<--------------->00<--------------->2
7<--------------->12<--------------->2
8<--------------->09<--------------->5
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.
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
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.
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.
I have a five and a three-gallon jar. Assuming there is 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.
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
How will you measure 15 minutes using two hourglasses of 7 minutes and 11 minutes respectively?
Let the hourglass with 7 minutes timeframe be x and the hourglass with 11 minutes timeframe be y.
Turn x and y together.
After seven minutes, turn x.
After 11 minutes, turn x again.
Now it will take 4 minutes for x to stop.
At that moment, you would have calculated 15 minutes.
You have 21 jars with you. Out of them, 7 are filled with water, 7 are half-full with water and 7 are empty. How will you distribute the jars among three people such that each one of them gets the equal number of jars and equal amount of water?
Give 3 full, 1 half-full and 3 empty bottles to the first person.
Give 3 full, 1 half-full and 3 empty bottles to the second person.
Give 1 full, 5 half-full and 1 empty bottle to the third person.
Charles walks over a railway-bridge. At the moment that he is just ten meters away from the middle of the bridge, he hears a train coming from behind. At that moment, the train, which travels at a speed of 90 km/h, is exactly as far away from the bridge as the bridge measures in length. Without hesitation, Charles rushes straight towards the train to get off the bridge. In this way, he misses the train by just four meters! If Charles would, however, have rushed exactly as fast in the other direction, the train would have hit him eight meters before the end of the bridge.
What is the length of the railway-bridge?
Let the length of the bridge be x meters.
Running towards the train, Charles covers 0.5x-10 meters in the time that the train travels x-4 meters. Running away from the train, Charles covers 0.5x+2 meters in the time that the train travels 2x-8 meters.
Because their speeds are constant, the following holds:
(0.5x-10) / (x-4) = (0.5x+2) / (2x-8)
which can be rewritten to
0.5x2 - 24x + 88 = 0
Using the abc formula we find that x=44, so the railway-bridge has a length of 44 meters.