A boat goes 15 km in an hour in still water, and takes thrice the time to cover the same distance upstream. The speed of the current (in km / hr) is –

A person rows a distance of $$ {3{3\over4}{ \ km}}$$ upstream in $$ {1{1\over 2}{\ hours}}$$ and a distance of 13 km downstream in 2 hours. How much time ( in hours) will the person take to row a distance of 90 km in still water?

A man can row $$7{1\over 2}km/h$$ in still water. If a river running at 1.5 km an hour, it takes him 50 minutes to row to a place and back, how far off is the place? 

A motorboat whose speed is 20 km/h in still water takes 30 minutes more to go 24 km upstream than to cover the same distance downstream. If the speed of the boat in still water is increased by 2 km/h, then bow much time will it take to go 39 km downstream and 30 km upstream?

A man can row 30 km upstream and 44 km downstream in 10 hours. Also, he can row 40 km upstream and 55 km downstream in 13 hours. The rate of the current is – 

A boat can row 15 km per hour downstream and 9 km per hour upstream. The speed (in km/hour) of the boat in still water is:

Speed of current is 10% of speed of boat in still water and the time taken by the boat to cover X km in downstream is 100% more than time taken by the boat to cover (X-45) km in upstream. Find the value of X?

A man can row 10 km/h in still water. When the river is running at a speed of 4.5 km/h, then it takes him 2 h to row to a place and comes back to the initial point . How far is the place (in km) (rounded off to two decimal places)?