A person can row a yacht along the stream at a speed of 9 km/h and against the stream at a speed of 7 km/h. The speed of the stream is:
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 1 km/h.
Given:
Downstream speed = x + y = 9
Upstream speed = x - y = 7
Calculations:
We have, x + y = 9 and x - y = 7 where
x and y are the speed of yacht and stream
Adding both equation, we get
⇒ x + y + x - y = 9 + 7
⇒ 2x = 16
⇒ x = 8
Now, use the value of x
⇒ x + y = 9
⇒ 8 + y = 9
⇒ y = 1 km/h