Answer:
6/3
Step-by-step explanation:
our average speed can be calculated in a couple different ways
is this case lets use a weighted average of the two speeds to find the average speed.
we know that that we were only going half as fast on the way back so it would take us twice as long
so our average speed would be (1/3) * 8 + (2/3) * 4
8/3 + 8/3 = 16/3 mph
another way to look at it is
to say we covered a total distance of 4 miles (2 out and 2 back)
the first 2 miles took us 1/4 of an hour since we were going at a rate of the 8 mph
the next 2 miles took us 1/2 of an hour since we were going at a rate of 4 mph
so we covered a distance of 4 miles in a time of 3/4 of an hour
distance = speed * time
speed = distance/time
speed = 4 /(3/4)
speed = 16/3 so either way we come up with the same answer
