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 tota

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Question 761684: 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 6 h. How far is the island from the harbor?
I can't figure out the formula to use to solve this problem. I know that rt=d
I got 20t for the 1st trip and 10(6-t) for the return trip, but now I don't know what else to do?
Found 2 solutions by Alan3354, lwsshak3:
Answer by Alan3354(69443) (Show Source):
You can put this solution on YOUR website!
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 6 h. How far is the island from the harbor?
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Avg speed for the round trip is
2*20*10/(20+10) = 40/3 mi/hr
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d = r*t = (40/3)*6 = 80 miles RT
40 miles each way

Answer by lwsshak3(11628) (Show Source):
You can put this solution on YOUR website!
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 6 h. How far is the island from the harbor?
let t=hrs to reach the island
6-t=hrs for return trip
distance=travel time*speed (same for both directions)
20t=10(6-t)
20t=60-10t
30t=60
t=2
20t=40
How far is the island from the harbor?40 miles