Replace the question mark with the correct number in the below-given picture?

The teacher told the student that if he told a lie then he will be expelled from school and if he told the truth then he still is expelled from school.

What can a student say to prevent his being expelled from school?

what does the below rebus means?

What is the four-digit number in which the first digit is one-third the second, the third is the sum of the first two, and the last is three times the second?

Can you find out which triangle will have a bigger area among the following?
1. A triangle with sides 300, 400 and 500
2. A triangle with sides 300, 400 and 700

A father's child, a mother's child, yet no one's son.

Who am I?

In the image below, you can see two glasses and two matchsticks.You need to move four matchsticks in such a manner that the crosses come inside the glasses. Note: you cannot move the crossed.

What can go through glass without breaking it?

What four weights can be used to balance from 1 to 30 pounds?

How many bananas can you eat if your stomach is empty?