If I went halfway to a town 60 km away at the speed of 30 km/hour, how fast do I have to go the rest of the way to have an average speed of 60 km/hour over the entire trip?

Riddle Answer# Hard Riddles

## Birthday Puzzle

The day before yesterday I was 25 and the next year I will be 28. This is true on only one day in a year. What day is my birthday?

Riddle Answer## Hidden Apple

There are 20 people in an empty, square room. Each person has full sight of the entire room and everyone in it without turning his head or body, or moving in any way.

Where can you place an apple so that all but one person can see it?

Riddle Answer## 17 Horses

A farmer wanted to divide his 17 horses among his three sons. According to the farmer, the oldest son should get half of the horses,the middle son should get one third of the horses and the youngest son should get one ninth of the horses.

When their father died they were not able to divide the horses as the result was coming in fractions. As the sons were fighting on how to divide the horses a traveling mathematician came and heard their problem. He proposed a solution with which all the sons got their share in the property without harming any animal.

What was the advice given and how the group of horses were divided?

Riddle Answer## 3 Boxes of Marbles

Three closed boxes have either white marbles, black marbles or both, and they are labeled white, black and both. However, all three boxes are mislabeled. You may reach into one of the boxes and pull out only one marble.

Which box should you remove a marble from to determine the contents of all three boxes?

Riddle Answer