Two trains are moving in opposite directions 60 km/hr and 90 km/hr. Their lengths are 1.10 km and 0.9 km respectively. The time taken by the slower train to cross the faster train in seconds is_________?

A. 36
B. 45
C. 48
D. 49

Explained with 5 Steps.
1.Data:
Speed 1 = 60 km/hr
Speed 2= 90 km/hr
Relative speed= (60+90)km/hr
Relative speed= 150 km/hr
Relative speed= 150×1000m/3600 Sec
Relative speed= 150,000m/3600 Sec
Relative speed= 1500m/36Sec
Relative speed= 42m/Sec
Distance 1= 1.10km
Distance 2= 0.9km
Total distance= (1.10+0.9) km
D(t)= 2 km => 2×1000m
D(t) = 2000m
2 Required:
Time=T=???
3. Formula:
S = V×T
For T
T= S/V
4. Solution:
Putting value in formulas.
T= 2000m/ 42 m/sec
T= 48Sec
5. Result:
Time =T= 48 Sec