Yes this puzzle is taken from the gear handle in the car, and those who drive their private cars must have noticed this calibration on the gear handle.

The correct answer is person 4, because he’s cutting the branch of the tree on which he is sitting, while 1 is just sitting on the branch and 2 & 3 are cutting the branches on which other people are sitting.

Step 1: Turn on two switches and keep them ON for a few minutes.

Step 2: Turn OFF one of the switch.

Step 3: Enter the room.

Step 4: if the bulb is ON, this means the switch that is ON is the correct switch.

Step 5: if the bulb is OFF, then touch the bulb.

Step 6: if the bulb is warm, this means that switch that you turned ON and then OFF, was the correct switch.

If the bulb is cold and normal, then the correct switch for the bulb is the third switch that was never turned ON.

The entire puzzle was a simple arithmetic but the question was twisted to misdirect your arithmetic calculation. If you examine the overall transaction, we can get this equation

$30 (initial payment) = $25 (paid to shop) + $2 (taken by sales person) + $3 (returned)

Confusion arises because the listener is forced to add the $2 to the $27 paid by the friends that makes the total $29. If you look carefully the $27 that they paid already includes the $2 taken by the sales person, so there is no need to add it again.

Now after the 3 dollar refund, the total transaction with the shop was only of $27, out of which the $25 was taken by the shop and $2 by the sales person.

The correct answer is, none, the question is wrong.

You can never add 3 odd numbers and get an even number as the result. Try out any three odd numbers.

For the puzzle we have 10 coins, so the odd numbers are 1, 3, 5, 7, and 9. If you add any of the 3 numbers from these, you will never get an even summation result that is 10.

The incorrect thing is the hand.

The answer is December 31^st. This question was asked to the man on 1^st of January, so day before yesterday on 30^th December he was 25, and on 31^st December he turned 26.

Now at the end of this year he will turn 27 and next year he will be 28.