Question 252959
We have to set up a RTD chart
hiker . . . . .rate . . . . .time . . . . . .distance
up . . . . . . .2 . . . . . . . d/2 . . . . . . . d
down . . . . .6 . . . . . . . d/6 . . . . . . . d
I assume he walks the same trail up and down, so that is the same distance.
time is distance / rate, so we have our 2 times.
we want average rate (speed). This is total distance over total time.
{{{2d / (d/2 + d/6)}}}
adding the fractions, we get
{{{2d / (4d/6)}}}
multiply by reciprocal, we get
{{{12d/4d}}}
His average rate is 3 mph