RRB JE exam Mathematics Important MCQs questions solved

Question No: 9

Two trains, each 100 m long, moving in opposite directions, cross each other in 8 seconds. If one is moving twice as fast the other, then the speed of the faster train is:

A.

30 km/hr

B.

45 km/hr

C.

60 km/hr

D.

75 km/hr

Answer: Option C

Explanation:

Let the speed of the slower train be x m/sec.

Then, speed of the faster train = 2x m/sec.

Relative speed = (x + 2x) m/sec = 3x m/sec.

https://www.indiabix.com/_files/images/aptitude/1-sym-tfr.gif

(100 + 100)

= 3x

8

https://www.indiabix.com/_files/images/aptitude/1-sym-imp.gif 24x = 200

https://www.indiabix.com/_files/images/aptitude/1-sym-imp.gif x =

25

.

3

 

So, speed of the faster train =

50

m/sec

3

 

​​ =

https://www.indiabix.com/_files/images/aptitude/1-sym-oparen-h1.gif

50

x

18

https://www.indiabix.com/_files/images/aptitude/1-sym-cparen-h1.gifkm/hr

3

5

   = 60 km/hr.