the loser of the above race had to run an extra 1600 m as terms of a bet. she runs the first 800 m at an average speed of 6 m/s and the next 800 m at an average speed of 8 m/s.
a. what is her total time needed to run 1600 m?
b. what is her average speed?

a. 233.3 s

First, we calculate the time the runner needs to cover the first 800 m:

where

is the speed in the first part

Substituting,

Similarly, the time needed to cover the second part was

So the total time the runner needed to finish the race was:

b. 6.86 m/s

The average speed can be calculated as follows:

where

is the total length of the race

t = 233.3 s is the time taken

Substituting,

hey , the answer is c