swimmer can swim a distance of 36 kilometer in the direction of water current in the same time ,which he requires to swim 36 kilometer in the opposite direction of water current in stream if in stil water swimmer has speed of 12 kilometer per hour more than the speed of that of water in stream then what is the speed of water? solve it with reference of formulas .
Answers
Answer:
0.75 hours
Step-by-step explanation:
If in still water the swimmer has a speed of 12 kilometer/ hour more than the speed of that of water in stream, and the speed of the stream is x kilometer/ hour, the speed of the swimmer with respect to the ground on the edges of the stream will be
12%2Bx kilometer/ hour in still water the swimmer,
12%2Bx%2Bx=12%2B2x kilometer/ hour in the direction of water current, and
12%2Bx-x=12 kilometer/ hour in the opposite direction of water current in stream.
With the same speed of the stream, it will take the swimmer a longer time to cover the same 36 kilometers when swimming against the current. How much longer depends on the current.
It will take the swimmer
36%2F12=3%29 hours to swim a distance of 36 kilometer in the opposite direction of water current in stream.
It will take the swimmer a shorter time,
36%2F%2812%2B2x%29 hours, to swim a distance of 36 kilometer in the direction of water current.
If it takes the swimmer t hours longer to cover the same 36 kilometers when swimming against the current,
36%2F%2812%2B2x%29=3-t
If we know x we can calculate t as t=3-36%2F%2812%2B2x%29
If we know t we can calculate x as 18%2F%283-t%29-6.
If the stream speed is x=3, then the downstream swim takes 2 hours and t=1 is the difference.
For x=9, t=1.8 and the swim downstream takes only 1.2 hours.
For x=12, t=2 and the swim downstream takes only 1 hour.
For x=18, t=2.25 and the swim downstream takes only 0.75 hours (45 minutes).