If Mark drives for 4 hours at 60 miles per hour and then drives another 5 hours at 80 miles per hour, what is his average speed, in miles per hour, for the trip?
ez
4 hrs at 60 mph = 240 miles
5 hrs at 80 mph = 400 miles
240 + 400 = 640
4 + 5 = 9
his average speed is 640/9 mph(approx. 71.1 mph)
ez
4 hrs at 60 mph = 240 miles
5 hrs at 80 mph = 400 miles
240 + 400 = 640
4 + 5 = 9
his average speed is 640/9 mph(approx. 71.1 mph)