The road from A to B is 10km uphill followed by 20km downhill, A motorcyclist averages 36km/h uphill and 90km/h downhill. Calculate the average speed

a. from A to B
b. from B to A

To find the average speed, we can use the formula:

Average Speed = Total Distance / Total Time

a. From A to B

Total Distance = 10km + 20km = 30km
Total Time = (10km / 36km/h) + (20km / 90km/h) = (0.2778 hours) + (0.2222 hours) = 0.5 hours

Average Speed from A to B = 30km / 0.5 hours = 60 km/h

b. From B to A

Total Distance = 20km + 10km = 30km
Total Time = (20km / 90km/h) + (10km / 36km/h) = (0.2222 hours) + (0.2778 hours) = 0.5 hours

Average Speed from B to A = 30km / 0.5 hours = 60 km/h

Therefore, the average speed from A to B and from B to A is 60 km/h.