INFOSYS INTERVIEW PUZZLES WITH ANSWERS

1. You are given two candles of equal size, which can burn 1 hour each. You have
to measure 90 minutes with these candles. (There is no scale or clock). Also u r
given a lighter.

Ans: 1. First light up the two ends of the 1st candle. When it will burn out light up
one end of the second candle. (30+60=90)

2. Try the similar problem to measure 45 minutes.

Ans: First light-up the two ends of the 1st candle and one end of the 2nd candle.

When the 1st candle will burn out ,then light up the both ends of the 2nd candle
(15+30=45)

3. You r given a thermometer. What can u do by this without measuring the
temperature?

Ans: if u put thermometer into a tree it won?t grow anymore, will just die off

4. How it is possible to place four points that are equidistance from each other?

OR
U r a landscape designer and your boss asked u to design a landscape such
that you should place 4 trees equidistance from each other.
(Distance from each tree to the other must be same)

Ans: Only 3 points can be equidistant from each other. But if u place points in the
shape of a pyramid then its possible

5. You are given a cake; one of its corner is broken. How will u cut the rest into
Two equal parts?

Ans: Slice the cake

6. How will you recognize the magnet & magnetic material & non-magnetic material?

Ans: Drag one piece of material over another. There is no attractive force in the
middle portion of the magnet.

OR
Get a piece of thread and tie up with the one bar and check for poles. If it iron bar
then it moves freely and if it is magnetic bar then it fix in one direction according to
poles.


7. If one tyre of a car suddenly gets stolen.... and after sometime u find the tyre
without the screws how will u make ur journey complete?

Ans: Open 3 screws, 1 from each tyre and fix the tyre.

8. How can u measure a room height using a thermometer?

Ans: temp varies with height. but its dependent on various other factors like
humidity, wind etc.

9. What is the height of room if after entering the room with a watch ur head
strikes a hanging bulb?

Ans: Oscillate the hanging bulb. Calculate the time period for one complete
oscillation by Simple Harmonic Motion (SHM) of the handing bulb. Put it in the
formula T=2 * 3.14 * (L/G)^1/2
L will be the length of the hanging thread.
Add the L with ur height to get the height of the room.

OR
Ans: Drop it from the room and find the time at which it strikes the floor. Using
physics formula s = (at^2)/2 (IM NOT SURE ABOUT THIS ONE)

10. Color of bear.... if it falls from 1m height in 1s.

Ans: We get 'g' perfect 10 which is only in poles...hence polar bear...color White

11. How will you measure height of building when you are at the top of the building?
And if you have stone with you.

Ans: Drop the stone and find the time taken for the stone to reach the ground. find
height using the formula
s = a + gt ( s = height, a= initial velocity=0, g=9.8m/s, t = time taken)

12. How wud u catch and receive a ball in same direction? (Dropping is from north
And receiving from bottom not accepted, as it is 2 directions)

Ans: ?

13. 25 statements given. Some tell truth, some false and some alternators. Find out
the true statements.

Ans: ?

14. Can u make 120 with 5 zeros?

Ans: Factorial (factorial (0)+factorial (0)+factorial (0)+factorial (0)+factorial (0)) =
120

15.There are three people A, B, C. Liars are of same type and Truth speaking people
are of same type. Find out who is speaking truth and who is speaking false from the
following statements:

a) A says: B is a liar.
b) B says: A and C are of same type.

Ans: lets assume A is speaking truth. It means B is a liar then it means A and C are
not of same type.

16.5 swimmers A, B, C, E, F and many conditions of their positions like there are
Two b/w A & F, B doesn't win etc the question was to find who was b/w like E & D?

Ans: ?

17. in a race u drove 1st lap with 40kmph and in the second lap at what speed u
must drive so that ur average speed must be 80kmph.

Ans: its impossible! if u drove the first lap in 40 kmph, its impossible that the
average speed of both the laps is 80kmph.

for eg. consider one lap distance = 80km.
time req. to cover 1 lap = 80km/40kmph = 2 hrs.

if the avg. speed is 80kmph, then the total time would have taken =

160kms/80kmph = 2 hrs.

same is the case with any other distance u consider. so the avg to be 80kmph is
impossible

18. You have to draw 3 concentric circles with a line passing thru their center
without lifting hand.

Ans: Start the line complete one circle move inside circles along the line and then
draw second circle. Like wise rest.

19. A rectangular paper is there. At a corner a rectangular size paper is taken from
it. Now you have to cut the remaining paper into two equal halves.

Ans: try it on the paper. You must fold the part that has complete paper and select
Half of it and then fold the part that cut and selects half of it and then cut along
the folding. (I DONT UNDERSTAND THIS ONE!!)

20. Value of (x-a)(x-b)???..(x-z)

Ans: 0 as there?s X-X term

21. There are 9 coins. 8 are of 1 gm and 1 is of 2 grams. How will you find out the
heavier coin in minimum number of weighing and how many weighing it will need?

Ans: 2 weighing ( Divide the number of coins into 3 parts at each weighing)