I have no doors but I have keys, I have no rooms but I have space, you can enter but you can’t leave! What am I?

Andrew’s doctor gives him three pills and tells him to take one every half hour. How much time will have passed by the time Andrew’s taken all three pills?

The doctor advised his patient to take a tablet after every fifteen minutes. He gave him five tablets in total.

How much time will he take to have all the five tablets?

I have a clock(12-hour format) and both the needles of the clock overlap at 12:00.
After how much time, they will overlap again?

Nine marbles are arranged in the image below. Can you slide two marbles to form a square?

A kind heart person buy packed food at 3$/packet from United states and sells them at 1$/packet at Africa. After some time he becomes a millionaire.

How come the guy become millionaire ?

Find the missing letter in the last circle logically in the given below picture.

Find the next number in the series

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

Replace the letters of words with a number so that the below equation holds true

BASE +
BALL
---------
GAMES
----------

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?