A train accelerating uniormly from rest attains a maximum speed of `40ms^(-1)` in `20s`. It travels at this speed for `20s` and is brought to rest with uniform retardation i further `40s`. What is the average velocity during this period?

Options

A. `80/3 ms^(-1)`
B. `40 ms^(-1)`
C. `25 ms^(-1)`
D. `30 ms^(-1)`

Answer

C