A ferry, when empty, travels twice as fast as when it is full. It travels 20 miles south with a cargo, spends 30 minutes for unloading, and returns to its original port empty in a total of 8 hours, what is the speed of the ferry when it is empty?
Solution
Correct Answer: Option A
Let, in 1 hours the ferry goes x km when loaded
and in 1 " " " " 2x " empty
According to question,
20/x + 20/2x = (8-0.5) hours
=> (40+20)/2x = 7.5
=> 60=15x
So, x=4
So, ferry goes (2×4)=8 km in 1 hours when it is empty.
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