Correct Answer - Option 4 : 75.7
Given :
Time taken by Deepti to cover 240 km = 3 hrs
Formula Used:
Distance = speed × time
Average Speed = 2 × S1 × S2/(S1 + S2)
Calculation:
⇒ Speed of Deepti in 1st part = 240/3 = 80 km/hr
⇒ Speed of Deepti in 2nd part = 20 × (18/5) = 72 km/hr
⇒ Average Speed = 2 × 80 × 72/152
⇒ 75.7 km/hr
∴ The average speed of deepti is 75.7 km/hr