Boats and Streams - General Aptitude

Q1:

A boat takes a total time of three hours to travel downstream from P and Q and upstream back from Q to P. What is the speed of the boat in still water?

I. The speed of the river current is 1 km per hour.

II. The distance between P and Q is 4 km.

A I alone sufficient while II alone not sufficient to answer

B II alone sufficient while I alone not sufficient to answer

C Either I or II alone sufficient to answer

D Both I and II are not sufficient to answer

E Both I and II are necessary to answer

ANS:E - Both I and II are necessary to answer

I. Speed of the current = 1 km/hr. II. PQ = 4 km. Let the speed of the boat in still water be x km/hr. Then,

4	+	4	= 3. This gives x.
(x + 1)		(x - 1)

Correct answer is (E).