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There are five men, let's say Tarun, Harish, Lavesh, Manoj and Manish.
All of them have a dot mark in their forehead. They can't see the dot on
their own forehead, but can see the ones on others. The owner of WHITE
dot is an honest person and will never lie, while the owner of BLACK dot
always tell the lie.
This are the statement from Tarun, Harish, Lavesh, and Manish:
Tarun: 'I see 3 whites and 1 black'
Harish: 'I see 4 black'
Lavesh: 'I see 3 black and 1 white'
Manish: 'I see 4 white'
What color is the dot on each Tarun, Harish, Lavesh, Manoj, Manish forehead?
Know color of dot on each forehead!
Source
Read this story first!
Let's take a look at who said what.
Tarun: 'I see 3 whites and 1 black'
Harish: 'I see 4 black'
Lavesh: 'I see 3 black and 1 white'
Manish: 'I see 4 white'
Harish and Manish made very contracting statements; so are statement of Tarun and Lavesh. That means, only one of them is telling the truth. Hence, only one of 4 have WHITE dot on his forehead. Till now we don't have idea of what Manoj had on his forehead. Even if he has WHITE dot then there can be maximum 2 WHITE dots among those 5.
Truth of Tarun and Manish:
Tarun and Manish must be lying as they are saying that they have seen 3 and 4 WHITE dots respectively. According to our first conclusion, there can be maximum 2 WHITE dots possible.
Truth of Harish:
Next if we assume Harish has WHITE dot and telling the truth then all other must be lying including Manoj and Lavesh. As per Lavesh, he had seen 3 BLACK and 1 WHITE dot. Now he must have seen BLACK dots on foreheads of Manoj, Tarun, Manish and WHITE dot on forehead of Harish as assumed. That mean he is telling truth though he has BLACK dot. But the man with BLACK is always lying, hence this case is also INVALID.
Truth of Lavesh:
So the only person left is Lavesh and must be telling the TRUTH with WHITE dot on his forehead. Hence, as his statement is suggesting, the Manoj must have WHITE dot and other three Tarun, Lavesh, Harish have BLACK dots (we already concluded these 3 are lying).
A car is crossing a 20km long bridge. The bridge can support at most
1500kg of weight over it. If somehow, the weight on the bridge becomes
more than that, it will break.
Now, the weight of the car is exactly 1500kg. At the midway, a bird
comes and sits on the roof of the car. This bird weighs exactly 200
gram.
Can you tell if the bridge breaks at this point or not?
Read what will happen next?
Source
What was the situation?
At first look, the first impression would be that the bridge will break certainly. But if you wait for a while before concluding anything you will get the right answer.
The bridge will not break in the case! It's 20 km long bridge & now it's in the middle of bridge after traveling 10 km. By now, it must have used half of the fuel that was in the tank initially at the start. This amount of fuel must be weighing more than 200 gm. Hence even a bird sits on the car there are hardly any chances the total weight on the bridge goes beyond 1500 kg! Hence, no chance of breaking of it.
