Puzzles for Week 2

Here are few puzzles that will help you to prepare for Interviews.

Puzzle 1:

Puzzle asked in one of Mu Sigma interviews: 
You are standing outside a room which is closed. There are three switches near the door of the room, all of which are off
  • There are 3 light bulbs in the room. One bulb for each switch
  • The room door is closed and there is no way to find which button corresponds to which bulb
  • You are only allowed to go into the room once 
  • Determine which switch corresponds to which bulb.

Squares in Chess

Puzzle 2:

Asked in many MBA interviews.
How many squares are present on a chess board?

If you thought that the answer is 64, then you are totally wrong.

Puzzle 3:

Read the conditions & answer the minimum steps to find correct label: 
  • There are 3 boxes with a label on top of each box 
  • The contents are: one box contains apples, other contains oranges & third contains both apples & oranges 
  • The labels are thus: A, O, AO 
  • All labels are misplaced
  • What is the minimum number of picks from the box (open the box & see) to correct the labels
Did you guess 2? If yes, then it’s wrong.


Here are some more puzzles that will help develop your gray cells.

Solution 1:

This puzzle needs you to think out of the box. How do you do that? What happens when you touch a light bulb which was kept turned on for some time?

  • Turn on one light switch for some time and then turn it off
  • Turn on another light switch and enter the room
  • The bulb which is glowing corresponds to the switch you just turned on
  • Touch other light bulb. 
  • If it's hot then it corresponds to the first switch. If it's cold then it corresponds to the third switch

Solution 2:

Puzzle Solution Chess
  • There are 64 smaller squares (8×8 of size 1×1) = 64 squares 
  • 4 1×1 squares form a bigger square - marked red (7×7 of size 2×2) = 49 squares 
  • Similarly, there are 6×6 of size 3×3 - marked green = 36 squares 
  • 5×5 of size 4×4 = 25 squares 
  • 4×4 of size 5×5) = 16 squares 
  • 3×3 of size 6×6 = 9 squares 
  • 2×2 of size 7×7 = 4 squares 
  • 1×1 of 8×8 size = 1 big square (the outline) 

Total – 64+49+36+25+16+9+4+1 = 204 squares

Do you see a pattern here? 
All these are squares of 1,2,3,.... So the answer is 8*(8+1)*(2*8+1)/6 - which is sum of squares of first 8 natural numbers.

Solution 3:

Read the final statement – “All labels are misplaced” 
  • Open first box, then you can know the correct label for this box
  • On the second box, the correct label is one which is not placed on it 
  • The final label will be the label that’s left 
  • Hence, only 1 pick is required.
Chance to win a Gift Card worth 100 rupees: If you have a better puzzles, send it to us.