Julie drives 100 mi to Grandmother's house. On the way to Grandmother's, Julie drives half the distance at 40.0 mph and half the distance at 60.0 mph . On her return trip, she drives half the time at 40.0 mph and half the time at 60.0 mph. Required:
a. What is Julie's average speed on the way to grandmother's house?
b. What is her average speed in the return trip?

a. The average speed on her way to Grandmother's house is 48.08 mph

b. The average speed in the return trip is 50 mph.

Explanation:

The average speed (S) can be calculated as follows:

Where:

D: is the total distance

T: is the total time

a. To find the total distance in her way to Grandmother's house, we need to find the total time:

Where v is for velocity

Hence, the average speed on her way to Grandmother's house is:

b. Now, to calculate the average speed of the return trip we need to calculate the total time:                        

Therefore, the average speed of the return trip is:

I hope it helps you!