Answer:
76.36km/h
Step-by-step explanation:
1. Calculate the distance covered during the first leg of the journey:
Distance = Speed × Time
Distance = 80 km/h × 3 hours = 240 km
2. Calculate the distance covered during the second leg of the journey:
Distance = 90 km/h × 2 hours = 180 km
3. Calculate the total distance for the entire journey by adding the distances from both legs:
Total Distance = 240 km (first leg) + 180 km (second leg) = 420 km
4. Calculate the total time for the entire journey:
The driver spent 3 hours driving during the first leg, and 2 hours driving during the second leg. There was also a 30-minute rest (0.5 hours) in between.
Total Time = 3 hours (first leg) + 0.5 hours (rest) + 2 hours (second leg) = 5.5 hours
5. Calculate the average speed for the whole journey:
Average Speed = Total Distance / Total Time
Average Speed = 420 km / 5.5 hours ≈ 76.36 km/h (rounded to two decimal places)