1) A boat started moving upstream with still water speed of 20

km/hr. It sailed for about 4 hr with the stream flowing only at 50% of

its normal speed. It then turned back moving downstream when

stream was flowing at 50% more speed than normal. It travelled like

that for 2 hr. If after that, the boat is found to be 10 km downstream

from its initial position, then what is the normal speed of the

stream

a) 6 km/hr b) 20 km/hr c) 10 km/hr d) 12 km/hr e) 8 km/hr

2) A boat started half an hour late but reached its desTtion half an

hour early due to decrease in the flow of the river. It had to reach in

7 hours. What is the percentage decrease in the flow of the river if

normally, a floating particle in the stream alone can float one-third

the distance to the desTtion by the same time in which the boat is

supposed to reach the desTtion in upstream direction?

a) 40 % b) 20 % c) 50 % d) 60% e) None of these

3) Time taken by a boat to travel a distance of 36 km downstream

with stream speed of (x + 1) km/hour is 12 minutes more than the

time taken by boat to travel the same distance downstream if the

stream speed is (x + 3) km/hour. Find the value of x if the speed of

boat in still water is 15 km/hour.

a) 1.5 b) 2.5 c) 3 d) 2 e) 5

4) A person starts swimming in downstream from point P on a lake

towards another point Q on the same lake. When he reaches at point

X exactly between P and Q the lake reverses its direction of flow and

remains same for the remaining journey. After reaching Q the

swimmer immediately started swimming towards P and reaches

there after travelling tor total of 2.5 hour. If the rate of current is 4

km/h and rate of swimmer is 12 km/h, then find the distance

between P and Q.

a) 14 km b) 16 km c) 18 km d) 10 km e) None of

these

5) A river is flowing at the speed of 2 km/hr. Boat A is running from

point X to point Y against the river and B is moving from point Y to

point X in the direction of flow of the river. The speed of boat A in

still water is 14 km/hr and the ratio of the speed of boat A while

travelling upstream to speed of boat B while travelling downstream

in the river is 3:4 respectively. Boat A and B start from their

respective sources simultaneously but after 4 hours 24 minutes due

to technical problem downstream speed of boat B reduces by 25%. If

both cross each other in 6 hours from the start then, find the

distance between X and Y.

a) 161.6 km b) 178.2 km c) 164.4 km d) 171.8 km e)

None of these