Correct Answer - Option 3 : 240 sec.
Given:
Distance covered by car = 400 m
Speed of car = 36 km/hr.
Distance covered by Truck = 8 km
Speed of truck = 40 m/sec.
Formula used:
Speed = Distancee/Time
1 km = 1000 m
1 hr. = 3600 sec.
Calculations:
Time taken by car
⇒ 36 km/hr = 400 m/T1
⇒ 36 × (5/18) = 400m /T1
⇒ T1 = 400/10
⇒ T1 = 40 sec.
Time is taken by truck
⇒ 40 m/sec. = 8 km/T2
⇒ 40 m/sec. = 8000 m/T2
⇒ T2 = 8000/40
⇒ T2 = 200 sec.
⇒ Sum of times = T1 + T2
⇒ Sum of times = 40 sec. + 200 sec.
⇒ Sum of times = 240 sec.
∴ The sum of the times is 240 sec.