There was an aeroplane crash, every single person died, but two people survived. How is this possible?

Make eight squares by moving only two matchsticks.
Note- Square can be of different sizes.

If,
9 * 8 * 7 = 65
8 * 7 * 6 = 50
7 * 6 * 5 = 37

Find
6 * 5 * 4 = ?

Solve the puzzle by telling what does below picture means.

John was working on a Chemical Mixture whose weight comprise 90% liquid and 10% solid. The total weight of the mixture is 20 pounds. After a while, John noticed that some of the liquid evaporated and now the liquid comprises just 50% of the weight.

What is the weight of the chemical mixture now?

Manish has to secure 40% marks to pass his B.tech final exams.
He got just 40 marks and failed by 40-marks.

What is the maximum marks?

One is to three as three is to five and five is to four and four is the magic number.
What is the pattern?

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

Who am I?

What number do you get when you multiply all of the numbers on a telephone's number pad?

I have a head like a cat and feet like a cat, but I am not a cat. What am I?