In a river, the ratio of the speed of the stream and the speed of a boat in still water is 5 : 7. Again, the ratio of the speed of the stream to the speed of another boat in still water is 6 : 8. What is the ratio of the speed of the first boat to that of the second boat in still water?
27 : 29
21 : 20
27 : 28
19 : 17
Explanation:
For the first boat let the speed of the stream be 5x and the speed of the boat be 7x.
For the 2nd boat, let the speed of the stream be 6y and the speed of the 2nd boat be 8y.
The speed of the stream will be the same.
∴ 5x = 6y
or x=6/5 y
Now, the required ratio of the speed of the first boat to that of the second boat = 7x : 8y
7*6/5y : 8y
[Putting x in terms of y]
y:
For the first boat let the speed of the stream be 5x and the speed of the boat be 7x.
For the 2nd boat, let the speed of the stream be 6y and the speed of the 2nd boat be 8y.
The speed of the stream will be the same.
∴ 5x = 6y
or x=6/5 y
Now, the required ratio of the speed of the first boat to that of the second boat = 7x : 8y
7*6/5y : 8y
[Putting x in terms of y]
y: