Subject: General Aptitude · Chapter: Boats and Streams · Exam: · Marks: · Difficulty:
What is the speed of the current? (R.B.I., 2004) I. Speed of the boat is 4 km/hr in still water. II. The boat runs at a speed of 6 km/hr down- stream. III. The difference between the speeds of the boat while travelling in still water and downstream is 2 km/hr.
(a)Only I and II
(b)Only III
(c)Any one of the three
(d)Only I and either II or III
(e)Either I and II together or only III
Answer
Answer (as printed): E
Explanation
Let the speed of the current be $x$ km/hr. Then, I. Speed downstream $=(x+4)$ km/hr, Speed upstream $=(x-4)$ km/hr. II. $x+4=6 \Rightarrow x=2$. III. Let the speed of the boat in still water be $y$. Then, $(y+x)-y=2 \Rightarrow x=2$. ∴ Either I and II together or only III are required. Hence, the correct answer is (e).
Explanation as extracted from the printed page; notation may be imperfect.