A man can swim 3 km/hr,in still water. If the velocity of the stream is 2 km/hr, the time taken by him to swim to a place 10 km upstream and back is :
1). $9\frac{1}{3}$ hr.
2). 10 hr.
3). 12 hr.
4). $8\frac{1}{3}$ hr.
Speed of a boat along and against the current are 12 km/hr and 8 km/hr respectively. Then the speed of the current in km/hr is
1). 5
2). 4
3). 3
4). 2
A man can swim at the rate of 4 km/ hr in still water. If the speed of the water is 2 km / hr, then the time taken by him to swim 10 km upstream is
1). $2\frac{1}{2}$ hrs
2). $3\frac{1}{2}$ hrs
3). 5 hrs
4). 4 hrs
A boy can swim in still water at a speed of 10 km / hr. If the speed of the current would have been 5 kmph,then the boy could swim 60km
1). upstream in 4 hour
2). downstream in 12 hours
3). upstream in 6 hours
4). downstream in 4 hours
A boat covers 12 km upstream and 18 km downstream in 3 hours , while it covers 36 km upstream and 24 km downstream in $6\frac{1}{2}$ hours.What is the speed of the current
1). 1.5 km/hr
2). 1 km/hr
3). 2 km/hr
4). 2.5 km/hr