How will you measure 15 minutes using two hourglasses of 7 minutes and 11 minutes respectively?

Solve the below puzzle by replacing the question mark with the correct number.

3 6 12

4 8 16

5 10 ?

Can you find the key in the picture below?

John is on an island and there are three crates of fruit that have washed up in front of him. One crate contains only apples. One crate contains only oranges. The other crate contains both apples and oranges.

Each crate is labelled. One reads 'apples', one reads 'oranges', and one reads 'apples and oranges'. He know that NONE of the crates have been labeled correctly - they are all wrong.

If he can only take out and look at just one of the pieces of fruit from just one of the crates, how can he label all of the crates correctly?

What's the next in the series?

H, Be, F, S, Mn, Kr, In, Gd, Tl, ?

Can you place six X (crosses) in below board without making three in a row in any way ?

A Man gave one of his sons 10 cents and another son was given 15 cents. What time is it?
Hint: Figure out the relation between time and number, is not so easy..:)

Move four matchsticks to the below square to form three squares?

If all Goats are Sheep and all Sheep are Deers, are all Deers Goats ?

What month of the year has 28 days?