| 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
