Physics
posted by JP .
An antelope has traveled 1.60 km at avg speed of 67.0 km/h. The antelope speed during the first half of the distance is 88km/h. Find the antelope's avg speed during the second half of the run.

The time is the distance divided by the velocity. The total time is the time at 88km/h + the time at the unknown speed v. Half the distance is run at each speed:
0.8/88 + 0.8/v = 1.6/67
.009091 + 0.8/v = .02388
.8/v = 0.01365
v = 58.6 km/h