Look at the below sequence of letters and tell us what the next letter should be:

O T T F F S S ?

There is a shop where written:
Buy 1 for $1
10 for $2
100 for $3
I needed 999 and still only paid $3. How could this be financially viable for the shop-keeper?

Find the next number in the series?
2, 12, 36, 80, 150, 252, 392, _ ?

Okay before we begin with the puzzle, do keep in mind that you have to answer it quickly.

You are participating in a car race. Seeking the perfect moment, you overtake the second person in the race. What positions are you in now?

There are three light switches outside a room. One of the switches is connected to a light bulb inside the room.
Each of the three switches can be either 'ON' or 'OFF'.

You are allowed to set each switch the way you want it and then enter the room(note: you can enter the room only once)

Your task is to then determine which switch controls the bulb?

You have a 12 liters jug full of water. You have two empty 8 liters and 5 liters jug. How can you divide the water into two equal parts using these jugs?

Make the seating arrangement of 10 children in such a way that there are 5 rows with 4 children in each row.

Find the missing number in the sequence below:

Can you replace the question mark with the correct number?

Which statement is true out of the following?
One statement here is false.
Two statements here are false.
Three statements here are false.