In calm water, what is the boat's speed? I. The downstream speed is 12 kmph. II. The upstream speed is 4 kmph. III. The boat's average speed on a to-and-fro voyage between two sites was 6 kmph.
A. I and II only
B. All I, II and III
C. III, and either I or II
D. Any two of the three
Answer:D
In calm water, what is the boat's speed? I. The downstream speed is 12 kmph. II. The upstream speed is 4 kmph. III. The boat's average speed on a to-and-fro voyage between two sites was 6 kmph.
A. I and II only B. All I, II and III C. III, and either I or II D. Any two of the three
Explanation: Based on I and II, the boat's speed in calm water is 1/2 (12 + 4) km/hr = 8 km/hr.We may deduce the following from II and III:We obtain 2 x 4 x y/4 + y = 6 when we use average speed = 2xy/x + y.24 + 6 = 8 years,y = 12.,1/2 (12 + 4) km/hr = 8 km/hr is the required speed.I and III, in turn, provide the solution.