Your doctor gives you pills to take one for every half hour. How long does it require to take all the pills ?

1. Half Hour
2. One Hour
3. One and Half Hour
4. Two Hours

Answer: One Hour

Explanation: You need one hour. You take the first pill at the beginning of the hour, then wait a half hour and take the second pill, then you wait another half hour and take the third and the last pill at the end of the hour.