Find the next number in the series

12, 20, 40, 72, 116, 172 ?

Can you name four days which start with the letter 'T'?

If you drop me I’m sure to crack, but give me a smile and I’ll always smile back. What am I?

I am a seven-letter word but if you remove four of my letters I will have one left. What word am I?

In a town, there are four houses located at different distances from each other. Following are the distances:

The third house is 60 meters apart from the first house.
The fourth house is 40 meters apart from the second house.
The third house is 10 meters nearer to the fourth house than it is to the second house.

Can you find out the distance between the fourth and the first house?

They came out at night, without being called.
They lost at day, without being stolen.
Who are they?

John drives to his office at 20km/hr. After reaching the office, he realizes that today is a holiday. He went back at an average speed of 30km/hr. Discounting the time spent in the stoppage what was the average speed of his journey?

What do you get if you add 2 to 100 four times?

I am white when I am dirty, and black when I am clean. What am I?

In Greek mythology, the Sphinx sat outside of Thebes and asked this riddle of all travellers who passed by. If the traveller failed to solve the riddle, then the Sphinx killed him/her. And if the traveller answered the riddle correctly, then the Sphinx would destroy herself. The riddle:

What goes on four legs in the morning, on two legs at noon, and on three legs in the evening?

Oedipus solved the riddle, and the Sphinx destroyed herself.