Answer:
It will take 1 hour.
Step-by-step explanation:
Given,
Speed of current = 6 miles per hour,
Let x be the speed of boat ( in miles per hour ),
So, the speed of fisherman,
In downstream = (x + 6) miles per hour,
In upstream = (x-6) miles per hour,
Since [tex]Time =\frac{Distance}{Speed}[/tex]
Thus, the time taken in 9 km downstream = [tex]\frac{9}{x+6}[/tex]
And, the time taken in 3 km upstream = [tex]\frac{3}{x-6}[/tex]
According to the question,
[tex]\frac{9}{x+6}=\frac{3}{x-6}[/tex]
[tex]\frac{3}{x+6}=\frac{1}{x-6}[/tex]
[tex]3x-18=x+6[/tex]
[tex]3x-x=6+18[/tex]
[tex]2x=24[/tex]
[tex]x=12[/tex]
Thus, the speed fisherman is 12 miles per hour.
Hence, the time taken to cover 12 miles is 1 hour.
