A boat goes a certain distance upstream and comes back downstream to the starting point in 72 min. If the speed of the boat in still water becomes 66.67% of the original, the time taken for the same journey will be 112 min. What is the ratio of the speed of the boat in still water and the speed of the current?
1
1 : 2
2
6 : 5
3
9 : 1
4
6 : 1
5
9 : 4