If a car travels 30.0 mi. north for 30.0 min., 50.0 mi. east for 1.00 hour, and 30.0 mi. south for 30.0 min., what is the average speed of the car over the total trip

Speed = (total distance covered) / (time to cover the distance).

The direction at any time during the trip doesn't matter.

This car traveled (30mi + 50mi + 30mi) = 110 miles.

The trip took (30min + 60min + 30min) = 120 minutes

The average speed for the trip was

(110 miles) / (120 minutes)

= (110 miles) / (2 hours)

= 55 miles/hour.