>>>>>>Data Scientist Tricky Interview Questions
##### A train 120 meters long is running with a speed of 60 km/hr. In what time will it pass a boy who is running at 6 km/hr in the direction opposite to that in which the train is going?
Speed of train relative to boy= `(60 + 6)` km/hr = 66 km/hr = [66 xx 5/18]` m/sec = `[55/3]` m/sec.
Time taken to pass the boy=` [120 xx 3/55]` sec = 6.54 seconds
##### What is the value of c , If 8 is 4% of a, and 4 is 8% of b. c equals b/a?
Let be the 4% of a is 4a/100. Since this equals 8, we have 4a/100=8. Solving for a yields a=8×`(100/4)`=200. Also, 8% of b equals 8b/100, and this equals 4.
Hence, we have `(8/100)`×b=4. Solving for b yields  b = 50. Now, c=`b/a`=`50/200`=`1/4.`
##### P and Q take part in 100 m race. P runs at 6kmph. P gives Q a start of 8 m and still beats him by 8 seconds. The speed of Q is:
`speed =( 6**5/18)m/sec) = (30/18) m/sec`
Time taken by P to cover 100 m = `(100 ** 18/30)`m/sec =60 sec
Time taken by Q to cover 92 m = (60 + 8) = 68 sec.
Q's speed =`("Distance"/"Time"**18/5) kmph =(92/68 ** 18/5)` kmph = 4.86kmph.
##### Find the speed of the train, if a train 142 m long passes a pole in 6 seconds.
Speed = `[142/6]` m/sec = `[23.6 ** 18/5]` km/hr = 84.9 km/hr
##### Sum of present ages of A, B and C is 92 years. If 4 years ago, the ratio of their ages were 1:2:3 respectively, find A’s present age.
Sum of present ages of A, B and C is = 92 years
Therefore , Sum of their ages 4 years ago = 92 – (4 * 3)= 80 years.
4 years ago ratio of the ages of A , B and C was = 1:2:3
Therefore, A’s age four years ago = `1/6` * 80 = 13.3 years.
So , A’s present age =13.3 + 4 = 17.3 years