Subject: General Aptitude · Chapter: Boats and Streams · Exam: · Marks: · Difficulty:
What is the speed of stream? (Bank P.O., 2004) I. The boat covers 24 km in 6 hours moving upstream. II. The boat covers 24 km in 3 hours moving downstream. III. The ratio between the speed of boat and stream is 3 : 1 respectively.
(a)Any two of the three
(b)I and II only
(c)II and III only
(d)I and III only
(e)All I, II and III
Answer
Answer (as printed): A
Explanation
I. Speed upstream $=\frac{24}{6}$ km/hr $=4$ km/hr. II. Speed downstream $=\frac{24}{3}$ km/hr $=8$ km/hr. III. Let the speed of the boat in still water be $3x$ km/hr. Then, speed of the stream is $x$ km/hr. ∴ Speed downstream $=\frac{1}{2}(3x+x)$ km/hr $=2x$ km/hr. Speed upstream $=\frac{1}{2}(3x-x)$ km/hr $=x$ km/hr.
Explanation as extracted from the printed page; notation may be imperfect.