Correct Answer - Option 1 : 28 km/h
Given:
Different speeds of Kunal: 25 km/h; 35 km/h, 20 km/h and 45 km/h
Distance covered by Kunal in 4 days = 50 km
Formula used
Speed = Distance/Time
Calculation:
Total distance travelled = 50 × 4 = 200 km
Total time taken = (50/25) + (50/35) + (50/20) + (50/45) = (887/126) hours
⇒ 2 + (10/7) + (5/2) + (10/9) hours
⇒ (252 + 180 + 315 + 140)/126 hours
⇒ 887/126 hours
Average speed of Kunal = 200 ÷ (887/126)
⇒ 28.41 km/h ≈ 28 km/h
∴ Average speed is 28 km/hr (approx)