SOLUTION: Elvin drove halfway from ashton to dover at 40 mi/h abd the rest of the way at 60 mi/h. What was his average speed for the whole trip? (Hint: let the distance for the whole trip be

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Question 29961: Elvin drove halfway from ashton to dover at 40 mi/h abd the rest of the way at 60 mi/h. What was his average speed for the whole trip? (Hint: let the distance for the whole trip be, say, 100 mi.)
Found 2 solutions by Earlsdon, jb007mi6:
Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
First, let's find the time it took Elvin to drive each leg of the trip.
First leg:
t1+=+d1%2Fr1 d1 = 40 miles and r1 = 40 mph.
t1+=+40%2F40
t1+=+1hour.
Second leg:
t2+=+d2%2Fr2 d2 = 40 miles and r2 = 60 mph.
t2+=+40%2F60
t2+=+2%2F3 hours.
Now we need to find the "weighted" average speed for the entire trip. Let's call that M.
M+=+%28r1%2At1+%2B+r2%2At2%29%2F%28t1%2Bt2%29
M+=+%2840%2A1+%2B+60%282%2F3%29%29%2F%285%2F3%29
M+=+%2840%2B40%29%2F%285%2F3%29
M+=+80%283%2F5%29
M+=+48mph.

Answer by jb007mi6(53) About Me  (Show Source):
You can put this solution on YOUR website!
average...40+60
----- = 50mph
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