Question

The speed of a stream is 2 mph. A boat travels 11 miles upstream in the same time it takes to travel 15 miles downstream. What is the speed of the boat in still water ?

Answer 1

The speed of the boat in still water is 15/11 mph.

Step-by-step explanation:

To find the speed of the boat in still water, we can use the formula: Speed of boat in still water = (speed downstream + speed upstream)/2.

Let's assume the speed of the boat in still water is 'b' mph.

Given that the speed of the stream is 2 mph, the speed downstream would be (b + 2) mph and the speed upstream would be (b - 2) mph.

Using the formula, we can set up the equation: (b + 2 + b - 2)/2 = 15/11.

Simplifying the equation, we get: 2b/2 = 15/11.

Canceling out the common factors, we get: b = 15/11.

Therefore, the speed of the boat in still water is 15/11 mph.