Good Riddles

 
Riddle #130 (medium)

Question: You work at a factory that produces dumbbell weights for lifting. One of the 10 machines has been producing weights that are always 1 pound less than the rest of the machines. You have a large scale used to weigh the weights for quality control. How could you find the defective machine by using the scale only once? You are allowed to make as many weights with the machines as you please.

Question: If you have an 11 minute and 13 minute hourglass, how can you accurately time 15 minutes?

Riddle #132 (medium)

Question: On a clock, how many times a day do the minute and hour hand overlap?

Riddle #133 (medium)

Question: There are three boxes labeled "Apples", "Oranges", and "Apples and oranges". Each box has the wrong label on it. How could you correctly label all three of the boxes by taking only one piece of fruit fruit from one of the boxes?

Question: You have a glass of water that looks about half full. How can you tell, only using the glass of water itself, if the glass is half full or not?

The glass is a right cylinder.