Frequently asked puzzles in Interview

Are you looking for a Job in IT industry or you think your aptitude and puzzle solving is good then this blog is for you. Just sorted down some commonly asked interview puzzles to me and my friends. Especially if you are from Pune area and searching a job in IT industry, you will definitely get one of these puzzles in interview. Go through this and comment below the puzzles you have been asked in interview.

• Candle problem

Two Candles of same height blows for 30 mins each. So how can we calculate 45 min by blowing this candle.

Note: you do not have scale, clock or any other measuring instrument.

Answer: Blow first candle from both the sides so that it will be finished in 15 minutes and then blow second candle from one side so this will take 30 minutes. Hence we will get total 45(15+30) minutes.

Tip: Instead of candle you can be asked a rope

• Bulb Problem

There is a bulb in a room and three switches in another room. These two rooms are on significant distance that no one can snoop into each other. You are given only one chance to go in room having bulb so how can you find the correct switch for that bulb? 

Answer: Turn on the first switch and wait for some time. Now turn off the first switch and turn on second switch. Go to the another room and check if bulb is blown. If bulb is blown second switch is answer. If bulb is not blown then touch the bulb if you feel heat then this is due to first switch is on for long time so first switch is answer. And if both the cases are false then third switch is answer. 

• 9 Coins Problem

There are total 9 coins out of which 8 coins are of same weight and one coin is of higher weight. How many minimum weighing are required to find out coin with higher weight.

Answer: 
Compare 6 coins at first weigh, 3 coins each in a balance

2 possibilities: 

   1. If both balance remain same then coin with higher weight is from other than this 6 coins. ie from remaining 3 coins

   2. If one of the balance move down then coin with higher weight is from 3 coins of this balance.

Now compare 2 coins second weigh, 1 coin each in a balance

2 possibilities:

   1. If both balance remain same then coin with higher weight is the third coin which is not in any balance.

   2. If one of the balance move down then coin with higher weight is in this balance

Hence only from 2 weighing coin is found.

• 3 steps up 1 step down

In a jump, a frog goes 3 feet up and move back 1 foot down. Then in how many jumps the frog reach the height of 19 feet.

Answer: Frog goes 3 feet up and move back 1 foot down. ie. Total 2 feet up in a jump.

Hence in 8 jumps = 8*2= 16 feet

And for 9^th Jump, Frog goes 3 feet up = 16+3 = 19 feet (reached the destination)

Hence total 9 jumps required.

• Tablet problem

There are 4 tablets. 2 tablets of one disease and 2 tablets of other disease. Both the tablets are of same size, shape with no color. You have to take one tablet of each now. So how could you make it?

Answer: You can cut each tablet in half and take the first half portion from it. In that way you can have one tablet of each disease.

Or else(if interviewer not happy with first answer)

You can take water in a glass dissolve the 4 tablets in it. Take the half solution now.

• L shape problem

There is a square of 4*4. Out of one 2*2 piece is missing.

How can you divide this L shape into 4 parts of same shape and size?

Answer: 

If you had gone through such puzzles in interview? Then Let me know in comments