Why is a manhole round? Why is it better to have round manhole covers compared to square manhole covers?

Riddle Answer# Hard Riddles

## Mail Valuable Object

Suppose you want to send in the mail a valuable object to a friend. You have a box that is large enough to contain the object and the box can be fitted with multiple locks.

Both of you also have several locks and their corresponding keys. However, your friend does not have the keys to any of your locks. If you send a key in an unlocked box, there is a danger of theft.

How can you send the object securely to your friend?

Riddle Answer## Two Trains and a Fly

Two trains travel toward each other on the same track, beginning 100 miles apart. One train travels at 40 mph (miles per hour); the other travels at 60 mph.

A fly starts flight at the same location as the faster train, flying at a speed of 90 mph. When it reaches the slower train, it turns around, flying the other direction at the same speed. When it reaches the faster train again, it turns around, and so on. When the trains meet, how far will the fly have flown?

Riddle Answer## 8 Coins 1 Counterfeit

You have 8 identical-looking coins. One of these coins is counterfeit and is known to be lighter than the others. You also have a two-pan balance scale. How can you identify the fake coin by using the scale only twice?

Riddle Answer## Cake 3 Cuts 8 Pieces

You must cut a birthday cake into eight equal pieces, but you’re only allowed to make three straight cuts, and you can’t move pieces of the cake as you cut. How can you do it?

Riddle Answer