Question

Jan walks 2 miles at a constant rate of 3 miles per hour and then runs 1 mile at a constant rate of 8 miles per hour.

Answer 1

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