Answer;
Average speed = 47.5 km/hr
Explanation and solution;
Average Speed = Total distance /Total time
Total distance;
-In the first two hours travelling at 40km/hr, total distance traveled is 80km.
(40 × 2) = 80 km
-In next two hours distance covered is 110 km. (55 ×2)
Total distance = 110 + 80 = 190 km
Total time = 2 + 2 = 4 hours
Average Speed = Total distance /Total time
= 190/4
= 47.5 km/hr