It's a protector.
It sits on a bridge.
One individual can see directly through it, while others wonder what it hides.

What is it?

What will be the best approach to finding all the prime numbers less than 75 that leave an odd reminder when we divide them with 5?

A dying old man wants to divide his entire land between his only two sons. Since his only wish is to treat them as equal as both of them have been too good to him, he wants to divide his land equally between them. The problem is that the land is significantly irregular in shape and thus there is no choice of cutting them into two equal halves.

Can you help him divide the land in a manner that both of his sons will be happy?

The answer I give is yes, but what I mean is no. What was the question?

Before Mount Everest was discovered, what was the highest mountain in the world?

You have a three-gallon and a five-gallon measuring device. You wish to measure out four gallons.

John and Jacob are playing bets. John gives $10 to Jacob and Jacob deals four cards out of a normal 52-card deck which are chosen by him completely randomly. Jacob keeps them facing down takes the first card and shows it to John. John has a choice of either keeping it or looking at the second card. When the second card is shown to him, he again has the choice of keeping or looking at the third which is followed by the third card as well; only if he does not want the third card, he will have to keep the fourth card.

If the card that John is choosing is n, Jacob will give it to him. Then the cards will be shuffled and the game will be played repeatedly. Now you might think that it all depends on chance, but John has come up with a strategy that will help him turn the favor in his odds.

Can you deduce the strategy of John?

I am a white box having no key or lid.
Yet there is a golden treasure inside it.

What Am I?

You can see it everyday, But cannot touch it at will. What is it?

I look at you, you look at me, I raise my right, you raise your left. What am I?