(11) A boat covers a certain distance downstream in 1 hour, while it comes back in 1.5 hours. If the speed of the stream is 3 km/hr, what is the speed of the boat in still water?
- (a) 9 km/hr
- (b) 12 km/hr
- (c) 15 km/hr
- (d) 18 km/hr
(12) If a boat goes 7 km upstream in 42 minutes and the speed of the stream is 5 km/hr, what is the speed of the boat in still water?
- (a) 10 km/hr
- (b) 12 km/hr
- (c) 14 km/hr
- (d) 16 km/hr
(13) A boat takes 3 hours to travel 15 km upstream and 15 km downstream. If the speed of the stream is 2 km/hr, find the speed of the boat in still water.
- (a) 8 km/hr
- (b) 10 km/hr
- (c) 12 km/hr
- (d) 14 km/hr
(14) A boatman goes 2 km against the current of the stream in 1 hour and goes 1 km along the current in 10 minutes. How long will it take to go 5 km in still water?
- (a) 2 hours
- (b) 2.5 hours
- (c) 3 hours
- (d) 3.5 hours
(15) A boat takes 20 hours to travel downstream and return to the starting point. If the speed of the boat in still water is 10 km/hr and the stream flows at 5 km/hr, find the distance covered downstream.
- (a) 50 km
- (b) 100 km
- (c) 150 km
- (d) 200 km
