A man can row 7 km/hr in still water. if the river is running at 3 km/hr, it takes 6 hours more in upstream than to go downstream for the same distance. how far is the place?
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Solution :-
☆ Let the place the man rows to be x and he rows back the same x distance.
In still water he rows at 6 kmph. When the current is 1.2 kmph, he goes to that place rowing at 6+1.2 = 7.2 kmph, and when he rows back his speed is 6–1.2 = 4.8 kmph.
The total time : x/7.2 + x/4.8 = 1, or
10x/72 + 10x/48 = 1, or
480x + 720x = 72*48, or
1200x = 72*48, or
x = 72*48/1200 = 2.88 km.
Check: Rowing downstream, time taken = 2.88/7.2 = 0.4 hour.
Rowing upstream, time taken = 2.88/4.8 = 0.6 hour.
Total time for rowing to and fro = 0.4+0.6 = 1 hour. Correct.
The place is 2.88 km downstream.
☆ ☆ ☆ Hop its helpful ☆ ☆ ☆
☆ Regards :- ♡♡《 Nitish kr singh 》♡♡
Solution :-
☆ Let the place the man rows to be x and he rows back the same x distance.
In still water he rows at 6 kmph. When the current is 1.2 kmph, he goes to that place rowing at 6+1.2 = 7.2 kmph, and when he rows back his speed is 6–1.2 = 4.8 kmph.
The total time : x/7.2 + x/4.8 = 1, or
10x/72 + 10x/48 = 1, or
480x + 720x = 72*48, or
1200x = 72*48, or
x = 72*48/1200 = 2.88 km.
Check: Rowing downstream, time taken = 2.88/7.2 = 0.4 hour.
Rowing upstream, time taken = 2.88/4.8 = 0.6 hour.
Total time for rowing to and fro = 0.4+0.6 = 1 hour. Correct.
The place is 2.88 km downstream.
☆ ☆ ☆ Hop its helpful ☆ ☆ ☆
☆ Regards :- ♡♡《 Nitish kr singh 》♡♡
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