A bicyclist makes a trip that consists of three parts, each in the same direction (due north) along a straight road. During the first part, she rides for 22 minutes at an average speed of 6.60 m/s. During the second part, she rides for 36 minutes at an average speed of 5.40 m/s. Finally, during the third part, she rides for 8.0 minutes at an average speed of 11.4 m/s.

Question

A bicyclist makes a trip that consists of three parts, each in the same direction (due north) along a straight road. During the first part, she rides for 22 minutes at an average speed of 6.60 m/s. During the second part, she rides for 36 minutes at an average speed of 5.40 m/s. Finally, during the third part, she rides for 8.0 minutes at an average speed of 11.4 m/s. 
What is her average velocity for the trip?

tchrwill · Answer

"Average" speed results from dividing the total distance by the total time.

Using V = D/T

The distance covered during the 1st part is 22x6.6mi.
The distance covered during the 2nd part is 36x5.4mi.
The distance covered during the 3rd part is 8x14.4mi.

Therefore, her "average" speed is (D1 + D2 + D3)/(T1 + T2 + T3)