Using the clues below, what four numbers am I thinking of?

The sum of all the numbers is 31.
One number is odd.
The highest number minus the lowest number is 7.
If you subtract the middle two numbers, it equals two.
There are no duplicate numbers.

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

When I go in I might cause pain. I cause you to spit and ask you not to swallow. I can fill your hole. What am I?

In the city of Brain Teasers, 5% of people do not list their phone numbers. Now if we select random 100 people from the phone directory, then how many people selected will have unlisted phone numbers?

What number should come in place of the question mark below?

100 prisoners are stuck in the prison in solitary cells. The warden of the prison got bored one day and offered them a challenge. He will put one prisoner per day, selected at random (a prisoner can be selected more than once), into a special room with a light bulb and a switch which controls the bulb. No other prisoners can see or control the light bulb. The prisoner in the special room can either turn on the bulb, turn off the bulb or do nothing. On any day, the prisoners can stop this process and say "Every prisoner has been in the special room at least once". If that happens to be true, all the prisoners will be set free. If it is false, then all the prisoners will be executed. The prisoners are given some time to discuss and figure out a solution. How do they ensure they all go free?

What's the next in the series?

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

What is wrong in the below Picture?

The picture shows the dice results in each couple of throws. If they are actually following a pattern, can you find out the missing one?

It walks on 4 when its young, walks on 2 when it's older, and walks on 3 when its very old?