## Boats and Streams

### Formulas

Speed = Distance/Time
D = S ✖ T
1. Speed of the boat/man in still water = U
2. Speed of the river/current = V
3. Speed downstream = U + V
4. Speed upstream = U - V
5. Time downstream = D / (U+V)
6. Time upstream = D / (U-V)

### Problems

1. A boat can travel with a speed of 12 kmph in still water. If the speed of the stream is 6 kmph, find the time taken by the boat to go 72 km down stream.
1. 2 hrs
2. 3 hrs
3. 4 hr
4. None of these
2. A boat can travel along with the stream with a speed of 20 kmph. The speed of the river is 5 kmph. What is the speed of the boat against the current?
1. 5 kmph
2. 10 kmph
3. 15 kmph
4. 8 kmph
3. A man rows 13 km upstream and 28 km downstream in 5 hr each. What is the speed of the river?
1. 1.5 kmph
2. 2 kmph
3. 2.5 kmph
4. 3 kmph
4. If a man rows at 6 kmph in still water and 4.5 kmph against the current, then his rate of rowing along the current is?
1. 9.5 kmph
2. 5. 25 kmph
3. 7.5 kmph
4. 9 kmph
5. A boat running upstream takes 9 hrs to cover a certain distance. It takes 6 hours to cover the same distance downstream. What is the ratio of the speed of the boat and speed of the river?
1. 3 : 2
2. 2 : 5
3. 5 : 1
4. 1 : 3

1. 3
2. 2
3. 1
4. 3
5. 3