Question

You travel 5 miles downstream in a kayak at a speed of r miles per hour. You turn around and travel 6 miles upstream at a speed of 0.6r miles per hour. Finally, you turn around and return to your original starting point at a speed of r+1 miles per hour.

Answer 1

Kyle, d = rt, right? This means that t = d/r. If we call the rate of the current c, then her rate upstream is hindered by the current and is 3 - c. Downstream is 3 + c. The total time is 6 hours... 5/(3 - c) + 5/(3 + c) = 6 Once we put everything over the same denominator, we don't need it anymore. 5(3 + c) + 5(3 - c) = 6(3 - c)(3 + c) 15 + 5c + 15 - 5c = 54 - 6c2
30 = 54 - 6c26c2 = 24c2 = 4c = 2 2 mph