## Boats and Streams

#### Boats and Streams

1. The speed of a boat downstream is 15 km/hr and the speed of the stream is 1.5 km/hr. The speed of the boat upstream is ?

1. Let the speed of boat in still water be x km/hr
Then, x + 1.5 = 15

##### Correct Option: C

Let the speed of boat in still water be x km/hr
Then, x + 1.5 = 15
⇒ x = 13.5

∴ Speed upstream = (13.5 - 1.5) km/hr = 12 km/hr

1. The speed of a boat in still water is 2km/hr. If its speed upstream be 1 km/hr, then speed of the stream is ?

1. Let the speed of stream be x km/hr
Then, speed upstream = (2 - x ) km/hr

##### Correct Option: C

Let the speed of stream be x km/hr
Then, speed upstream = (2 - x ) km/hr
⇒ 2 - x = 1
∴ x = 1 km/hr

1. A man can row downstream at 14 km/hr and upstream at 9km/hr. Man's rate in still water is ?

1. Man's rate in still water = (14 + 9)/2 km/hr

##### Correct Option: C

Man's rate in still water = (14 + 9)/2 km/hr = 11.5 km/hr

1. A man can row with the stream at 11 km/hr and against the stream at 8 km/hr. The speed of the stream is ?

1. Speed of stream = (11 - 8)/2 km/hr

##### Correct Option: C

Speed of stream = (11 - 8)/2 km/hr = 1.5 km/hr

1. The speed of a boat in still water is 2 km/hr. If its speed upstream be 1 km/hr, then speed of the stream is ?

1. Speed in upstream = Speed in still water - Speed of stream.
∵ 1 = 2 - x

##### Correct Option: C

Speed in upstream = Speed in still water - Speed of stream.
∵ 1 = 2 - x
∴ x = 2 - 1 = 1 km/hr