![A man can swim in still water at 8 km/hr. If the river is flowing at 2km/hr he takes 80 minutes to reach a place and return back, how far is the place?](https://www.gkseries.com/blog/wp-content/uploads/2023/07/A-man-can-swim-in-still-water-at-8-km-hr.-If-the-river-is-flowing-at-2km-hr-he-takes-80-minutes-to-reach-a-place-and-return-back-how-far-is-the-place.jpg)
Question | A man can swim in still water at 8 km/hr. If the river is flowing at 2km/hr he takes 80 minutes to reach a place and return back, how far is the place? | |
Type | multiple_choice | |
Option | 4 km | incorrect |
Option | 3 km | incorrect |
Option | 4.5 km | incorrect |
Option | 5 km | correct |
Let the place is X km far.
Speed downstream = 8+2=10 km/hr
Speed upstream = 8 – 2 = 6 km/hr
Time = Distance / Speed
x/6 + x/10 = 80/60
10x+ 6x/60 = 4/3
30X + 18X = 240
48X = 240
x = 240/80 = 5 km