How will you measure 15 minutes using two hourglasses of 7 minutes and 11 minutes respectively?

Can you complete the sequence puzzle?

AR TA GE CA LE VI LI _

There are are five things wrong with this sentence; only geniuses will be able to to spot all of the mitstakes

Look at this sequence from top to bottom. What is the next number in the sequence?
1
11
21
1211
111221
312211

What does the below mathematical rebus mean?

Why is the Hole below a Lock?

I make a loud sound when I’m changing. When I do change, I get bigger but weigh less. What am I?

A frog is at the bottom of a 30-meter well. Each day he summons enough energy for one 3-meter leap up the well. Exhausted, he then hangs there for the rest of the day. At night, while he is asleep, he slips 2 meters backwards. How many days does it take him to escape from the well?

It spends most of its day eating white, but when it’s quick enough, it gets to eat fruit and sometimes some blue things. It’s in a dark room, where the walls are blue, it runs from a ghost that roams the halls and haunts it all the time. What is it?

What does this mathematical rebus means ?