1) during his morning commute to work in rush hour traffic, justin's average speed was 30 mi/h. during his afternoon commute back home along the same route, his average speed was 60 mi/h. what was his average speed for the entire round trip?

15 points, answer correctly, !

45 mi/h

Step-by-step explanation:

Recall: Speed = distance / time

Let the time taken for the morning journey be and the time taken for the afternoon journey be ,and the distance covered be d

that means for the first journey,

30 =

d = 30

Also for the afternoon journey,

d = 60

Equating the two , since the same distance is being covered , we have

30 = 60

that is

=

= 2

Also ,

total distance covered = 30 + 60

Average speed = total distance / total time

 = 30 + 60 / +

  Recall that   = 2 , substitute this  into the formula for average speed , then we have

Average speed = 30(2) +60 / 3

Average speed = 120 / 3

Therefore :

Average speed = 40 mi/hr

f(x) has value 150 at x= 0

and 0 at x= 3

so d(f(x))/dt = slope = -150/3 = -50