Question

The speed of a motor boat in still water is 7km/hr. If the speed of the motor boat against the stream is 5 km/hr, what is the speed of the stream?

• A. \(1.5 \text{ km/hr}\)
• B. \(2 \text{ km/hr}\)
• C. \(2.5 \text{ km/hr}\)
• D. \(1 \text{ km/hr}\)

Hint:

Remember, the speed of the boat in still water minus the speed against the stream gives you the speed of the stream.

Answer 1

The Correct Option is A

Given:

• Speed of the boat in still water (\(u\)) = 7 km/hr
• Speed of the boat against the stream = 5 km/hr

The speed of the boat against the stream is calculated as:

    u - v = 5  (km/hr)
  

Substitute the value of \( u \):

    7 - v = 5
  

Solving for \( v \):

    v = 7 - 5
    v = 2 km/hr
  

Thus, the speed of the stream is 2 km/hr, which matches option (b).