A man rows down a river 15 km in 3 h with the stream and returns in  The rate at which he rows in still water is

• 2.5 km/h

• 1.5 km/h

• 3.5 km/h

• 4.5 km/h

A boat goes 15 upstream and  downstream in 3 hours 15 minutes. It goes 12 km upstream and 14  km downstream in 3 hours. What is the speed of boat in still water.

• 4 km/hr

• 6 km/hr

• 10 km/h

• 14 km/hr