Math - finding out average speed?

Question

you drive to the beach at a rate of 120 kilometers per hour. on the return trip, you drive at a rate of 60 kilometers per hours. what is your average speed for the entire trip?

Answer 1

First, make up a one-way distance to the beach - any number will work, but I will pick 120 km for this example.

Using distance=rate*time, the first trip time is (120 km)/(120 km/hr) = 1 hour.

The return trip time is (120 km)/(60 km/hr) = 2 hours.

The total time traveled was 3 hours and you traveled a total of 240 km.  Therefore the average speed was (240 km)/(3 hours) = 80 km/hr.

Answer 2

:)

first you add the two speeds together, then you divide by two. Why two? Because thats the two speeds shown in this example.

120+60= 180

180/2= 90.

90 kilos is the average speed. Hope this helps