Correct Answer - Option 1 :
\(34 \frac 2 7\) km/h
Given:
Distance traveled in one side = 120 km
Speed while going = 40 km/h
Speed while returning = 30 km/h
Formula used:
Average speed = Total distance travelled/Total time taken
Calculation:
Time taken while going = (120/40) hr
= 3 hrs
Time taken while returning = (120/30) hr
= 4 hr
Total distance travelled while going and returning = (120 × 2) km
= 240 km
∴ Average speed of the truck = (240/7) km/h
= \(34 \frac 2 7\) km/h