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

Solve the following series:
AZ, GT, MN, __, YB

A boy was driving a car, a girl took a lift from her. She asked his name. The boy said - my name is hidden in my car’s number, find it if you can. After this, she got down Car number was [ WV733N ] Can you guess the name now?

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

Find
6 * 5 * 4 = ?

Next Number in the Series,

5, 16, 49, 104, ?

In front of you, there are 9 coins. They all look absolutely identical, but one of the coins is fake. However, you know that the fake coin is lighter than the rest, and in front of you is a balance scale. What is the least number of weightings you can use to find the counterfeit coin?

How many cubic feet of dirt are in a hole of one foot deep, three feet long, and two feet wide?

There is a barrel with no lid and some wine in it. 'This barrel of wine is more than half full,' said Curly. 'No it's not,' says Mo. 'It's less than half full.' Without any measuring implements and without removing any wine from the barrel, how can they easily determine who is correct?

Complete the series by replacing "?" with the correct number.

ST ND RD TH '?'

How many times in a given day, minutes and hour clock comes in a straight line ?