A candidate had appeared in an interview in a renowned company. While answering the question, he became quite nervous. The interviewer was generous and he ordered coffee for him. He kept the coffee before him. Before the candidate could take a sip, he was asked by the interviewer 'What is before you?'
He smiled and replied 'Tea'. The interviewer hired him immediately. Why?
You are given a set of scales and 12 marbles. The scales are of the old balance variety. That is, a small dish hangs from each end of a rod that is balanced in the middle. The device enables you to conclude either that the contents of the dishes weigh the same or that the dish that falls lower has heavier contents than the other.
The 12 marbles appear to be identical. In fact, 11 of them are identical, and one is of a different weight. Your task is to identify the unusual marble and discard it. You are allowed to use the scales three times if you wish, but no more.
Note that the unusual marble may be heavier or lighter than the others. You are asked to both identify it and determine whether it is heavy or light.
So that the following plan can be followed, let us number the coins from 1 to 12. For the first weighing let us put on the left pan coins 1,2,3,4 and on the right pan coins 5,6,7,8.
There are two possibilities. Either they balance, or they don't. If they balance, then the different coin is in the group 9,10,11,12. So for our second one possibility is to weigh 9,10,11 against 1,2,3
(1) They balance, in which case you know 12 is the different coin, and you just weigh it against any other to determine whether it is heavy or light.
(2) 9,10,11 is heavy. In this case, you know that the different coin is 9, 10, or 11, and that that coin is heavy. Simply weigh 9 against 10; if they balance, 11 is the heavy coin. If not, the heavier one is the heavy coin.
(3) 9,10,11 is light. Proceed as in the step above, but the coin you're looking for is the light one.
That was the easy part.
What if the first weighing 1,2,3,4 vs 5,6,7,8 does not balance? Then any one of these coins could be the different coin. Now, in order to proceed, we must keep track of which side is heavy for each of the following weighings.
Suppose that 5,6,7,8 is the heavy side. We now weigh 1,5,6 against 2,7,8. If they balance, then the different coin is either 3 or 4. Weigh 4 against 9, a known good coin. If they balance then the different coin is 3, otherwise it is 4. The direction of the tilts can tell us whwther the offending coin is heavier or lighter.
Now, if 1,5,6 vs 2,7,8 does not balance, and 2,7,8 is the heavy side, then either 7 or 8 is a different, heavy coin, or 1 is a different, light coin.
For the third weighing, weigh 7 against 8. Whichever side is heavy is the different coin. If they balance, then 1 is the different coin. Should the weighing of 1,5, 6 vs 2,7,8 show 1,5,6 to be the heavy side, then either 5 or 6 is a different heavy coin or 2 is a light different coin. Weigh 5 against 6. The heavier one is the different coin. If they balance, then 2 is a different light coin.
Step1. Lets say y = x
Step2. Multiply through by x xy = x2
Step3. Subtract y2 from each side xy - y2 = x2 - y2
Step4. Factor each side y(x-y) = (x+y)(x-y)
Step5. Divide both sides by (x-y) y = x+y
Step6. Divide both sides by y y/y = x/y + y/y
Step7. And so... 1 = x/y + 1
Step8. Since x=y, x/y = 1 1 = 1 + 1
Step9. And so... 1 = 2
Step 5 is invalid, because we are dividing by (x-y), and since x=y, we are thus dividing by 0. This is an invalid mathematical operation (division by 0), and so by not following basic mathematical rules
There is a 30km long bridge. The bridge can only support up to a weight of 2000 kg. A car that weighs 2000 kg needs to cross that bridge. When the car has reached midway of the bridge, a bird comes and sits on top of the car. The bird weighs 300 grams.
Now, does the bridge breaks down at this point of time or not?
A square island comprised of a square castle. A 14m wide trench surrounded the island from everywhere. Roman Empire wanted to invade the castle and gain the loot as well as possession of the island. They brought along wooden planks to cross the trench. However, they realized that the planks were just 13m long.
How did they use those planks to invade as well as capture the island ?
Stephen died of heart attack. His soul was received in heaven. He was astonished to find himself as young as he had been in his young adult age. He looked around and there were thousands of young and naked people. His eyes searched to find someone familiar and suddenly he noticed Adam and Eve.
A mastermind organized a quiz competition in which six selected candidates were invite namely James Hunt, Ruxandra Bar, Sophia Connors, David Finch, Fred Odea and Brian Miller. A 'special puzzle' was asked to all of them. The first one to answer it was promised for a big award.
After that, the candidates were offered the meal before the mastermind stood up to announce the much awaited result. He started announcing:
'Ok now everybody!'
'The winner of…..'
'The Hardest Riddle Ever Event.'
And then he smiled. All the candidates understood who won.
Just look at the announcement lines. The first sentence in 'Ok now everybody!' If you take out just the first letter of every word, it will form 'ONE'. In the same manner the second sentence 'The winner of…..' will give form 'TWO' and the third sentence 'The Hardest Riddle Ever Event.' Will form THREE.
Thus the final sentence must form FOUR. There is only one candidate who can suffice with the first two letter and he is Fred Odea. The final sentence of the mastermind must be, 'Fred Odea: Ultimate Riddler!'