Infosys Reasoning (Recent) - 1

Infosys Reasoning (Recent) - 1

1.       There is a number that is little less than 500, which when divided by 3,4,5,7 leaves no remainder. Find the number.  (3 marks)
Ans: 420
The answer is the LCM of 3,4,5,7 that is 420.

Similar questions have come in other papers, where it is said there will be a remainder of 1. In that case the answer would be 420 + 1 = 421.  

2.       One day Harry and I set our watches together. We were not aware that my watch was going faster by 2 min per hour and Harry’s watch was going slower by 1 min per hour. After sometime, we discovered that my watch was one hour ahead of Harry’s watch.  After how much time we noticed this?  (3 marks)                     
Ans: 20 hours.

For every hour the difference between the two watches was 2 + 1 = 3 minutes.

The difference in time between the two watches was one hour and Harry’s watch was ahead of mine.

Thus the number of hours elapsed is 60minutes / 3 minutes -> 20 hours.  

3.       There is well of depth 30m and a frog is at the bottom of the well. The frog jumps 3m in one day and falls back by 2m in the same day. How many days it would take the frog to come out of the well?

Ans: The frog would come out on the 28^th day.

Every day the frog climbs up net 1m. On the 27^th day it will be 3m below the top of the well and on the 28^th day when it jumps 3m it would come out of the well.

4.       If 5/2 artists make 5/2 paintings using 5/2 canvases in 5/2 days then how many artists 
are required to make 25 paintings using 25 canvases in 25 days? 

Ans: 25. (The only inverse variable is artists and days and the other two are direct variables)

5.       If I walk with 30 miles/hour I reach 1 hour before and if I walk with 20 miles/hour I reach 1 
hour late. Find the distance between 2 points and if the exact time of reaching destination 
is 11 am then find the speed at which I walk. 
Ans: 120miles and 24 miles/hour

Let D be the distance. Then we have one straight equation -> D/20 – D/30 = 2 hours.

Solving this we get the value of D as 120 miles.

Now walking at 20 miles/hour I am late by one hour. This speed would take me six hours to cover the distance and I am late by one hour. In other words I should cove the distance in 5 hours. Then my speed will have to be 120 / 5 = 24 miles/hour. This applies when I walk at 30 miles/hour in which case I am earlier by one hour. 

6.       The product of 5 different temperatures is 12. If all of them are integers then find all the 
temperatures.
Ans:  -2, -1, 1, 2, 3 

7.       There are 9 cities numbered 1 to 9. From how many cities the flight can start so as to 
reach the city 8 either directly or indirectly such the path formed is divisible by 3. 
Ans: Three cities 1, 3 and 6.

City 1 – The path will be 2, 3, 4, 5, 6, 7,

City 3 -  The path will be 2, 1, 9

City 6 -  The path will be 5, 4, 3, 2, 1, 9

8.       Sometime after 10:00 PM a murder took place. A witness claimed that the clock 
must have stopped at the time of the shooting. It was later found that the position of 
both the hands were the same but their positions had interchanged. Tell the time of the 
shooting (both actual and claimed). 
Ans: Time of shooting -> 11:54 PM  Claimed Time -> 10:59 PM. 

9.       What is the next number in the series is 1 , 2 , 4 , 13 , 31 , 112 , ? 
Ans: 224. 
No number has digits more than 4. All of them are 1 , 2, 4, 8 , 16 , 32 , 64 converted to 
numbers in base 5.

10.   Shahrukh speaks truth only in the morning and lies in the afternoon, whereas 
Salman speaks truth only in the afternoon. A says that B is Shahrukh. Is it morning or 
afternoon and who is A - Shahrukh or Salman? 
Ans: Afternoon.  A is Salman.

Since A says that B is Shahruk, A can only be Salman and he speaks truth only in the afternoon.

            If A is Shahrukh then his saying B is Shahrukh is a lie. He lies in the afternoon.

11.   There are 6 volumes of books on a rack kept in order ( ie vol.1, vol. 2 and so on ). 
Give the position of the books after the following changes have been made. 
Vol. 5 was directly placed to the right of Vol. 2.  Vol. 4 has Vol. 6 to its left and both 
were not at Vol. 3's place. Vol. 1 has Vol. 3 on right and Vol. 5 on left. An even numbered 
volume is at Vol. 5's place Find the order in which the books are kept now. 
Ans: 2, 5, 1, 3, 6, 4. 

12.   I bought a car with a peculiar 5 digit numbered licence plate which on reversing 
could still be read. On reversing value is increased by 78633.Whats the original number 
if all digits were different? 
Ans: 10968

Only 0 1 6 8 and 9 can be read upside down. So on rearranging these digits, we get 
the answer as 10968. 

13.   Two trains starting at same time, one from Bangalore to Mysore and other in 
opposite direction arrive at their destination 1 hour and 4 hours respectively after passing 
each other. How much faster is one train from other? 
Ans: Twice. 
Let ‘x’ be the distance between Bangalore & Mysore and let ’a’ be the distance from Bangalore to the meeting point.

Train 1 from BNG to MYS speed be S1.  Train 2 from MYS to BNG speed be S2.

Then we have -> a/S1 = x-a/S2 -> S1/S2 = a/x-a.

Train 1 takes 1 hour to travel (x-a) distance and Train 2 takes 4 hours to travel the distance ‘a’. So we have (x-a)/S1 = 1 hour and a/S2 = 4 hours. Substituting these values

We have S1/S2 = 4S2/S1 -> S1^2 = 4S2^2 Thus S1 : S2 = 1 : 2.