Infosys Puzzles

1.There is a escalator and 2 persons move down it.A takes 50 steps and B takes 75 steps while the escalator is moving down. Given that the time taken by A to take 1 step is equal to time taken by B to take 3 steps. Find the no. of steps in the escalator while it is stationary.
100 Steps 110 Steps 120 Steps 130 Steps

2.If 5/2 artists make 5/2 paintings using 5/2 canvases in 5/2 days then how many artists r required to make 25 paintings using 25 canvases in 25 days?
25 26 27 24

3.If the digits of my present age are reversed then i get the age of my son.If 1 year ago my age was twice as that of my son.Find my present age.
Father - 72, Son - 38 Father - 71, Son - 39 Father - 73, Son - 37 Father - 73, Son - 38

4.There are 6561 balls out of them 1 is heavy. Find the minimum number of times the balls have to be weighed for finding out the heavy ball.
7 8 9 10

5.If I walk with 30 miles/hr I reach 1 hour before and if I walk with 20 miles/hr I reach 1 hour late. Find the distance between 2 points and the exact time of reaching destination is 11 am then find the speed with which it walks.
120miles and 24 miles/hr 121miles and 24 miles/hr 122 miles and 24 miles/hr 123 miles and 24 miles/hr

Explanation
1.If A takes 1 step in one second, then B takes 3 steps in one second. If A takes t1 seconds to take 50 steps, then B takes 150 steps in t1 seconds. For B, to take 150 steps he requires t1 seconds, then to take 75 steps he requires t1/2 seconds. So now, s1=50, t1 = t1 & s2=75, t2=t1/2 ans= (s1*t2 ~ s2*t1) / t1 ~ t2) which gives 100. So 100 steps is the answer
2.More artist more paintings(direct proportion)
More artist more canvas (direct proportion)
More artist less days (indirect proportion)
Thus,
((5/2)*(5/2))/((5/2)*(5/2)) = x*25/25*25

Solving above equation we get,

x = 25

Thus 25 artist are required..
3.For this kind of questions you should go through the options, that is the best way to solve them. Just check with each of four options till we get the correct one.
4.Divide the balls into three groups.

• Weigh two groups on the scale, if they are euqal third group has heaviest ball, else the group with more weight has the heaviest ball.
• Repeat above steps with the heaviest group

So the answer is log3(6561) = 8

5.Let d be the distance to destination.

When he walked at speed 30 miles/hour, time taken to cover the distance = d/30 hours
When he walked at speed 20 miles/hour, time taken to cover the distance = d/20 hours
Gven that d/20 - d/30 = ( 1 + 1) = 2 hours
On solving this we'll get d = 120miles

Now we need to find the normal speed with which he walks
It's given that whe he walks at 30 miles/hours, he reaches 1 hour early.
So, when he walks with 30 miles/hour speed, time taken = 120/30 = 4hours.
Thus he will take 5 hours at his normal speed.
=> Normal speed = 120/5 = 24 miles/hours