Answer:
12 mph
Step-by-step explanation:
Given that:
Total distance traveled = 78 miles
Time taken, t = 6 hours
Average speed for first 30 miles = 15 mph
Time taken = distance / speed
Time taken = 30 / 15
Time taken = 2 hours
Average speed for last 48 miles = x
Time taken to travel last 48 miles = (6 - 2) = 4 hours
Average speed for last 48 miles :
Distance traveled / time taken
48 miles / 4 hours
= 12 mph
