SOLUTION: A ferry leaves a harbor and travels to a resort island at an average speed of 20 mph. On the return trip, the ferry travels at an average speed of 10 mph because of fog. The total

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Question 418987: A ferry leaves a harbor and travels to a resort island at an average speed of 20 mph. On the return trip, the ferry travels at an average speed of 10 mph because of fog. The total time for the trip is 3 h. How far is the island from the harbor?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let d = distance to island from harbor
given:
Trip to island:
+d+=+20%2At1
Trip back:
d+=+10%2At2
-----------
t1+%2B+t2+=+3
This is 3 equations and 3 unknowns,
so it's solvable
----------
t1+=+d%2F20
t2+=+d%2F10
and
d%2F20+%2B+d%2F10+=+3
d+%2B+2d+=+60
3d+=+60
d+=+20
The island is 20 miles from the harbor
check:
20+=+20%2At1
t1+=+1
and
20+=+10%2At2
t2+=+2
1+%2B+2+=+3
OK