Question

Fran swims at a speed of 2.6 mph in still water. The Lazy River flows at a speed of 0.4 mph. How long will it take Fran to swim 1.1 mi​ upstream? 1.1 mi​ downstream?

Answer 1

Upstream = 0.5 hour.

Downstream = 0.366 hour.

Explanation:

Speed of fram in still water (u) = 2.6 mph.

Speed of water (v) = 0.4 mph .

Time taken by fran to swim 1.1 mi upstream.

Speed upstream = u - v = (2.6 - 0.4) mph = 2.2 mph

So the time taken =
`(distance)/(speed) = (1.1)/(2.2)` = 0.5 hour.

Time taken by fran to swim 1.1 mi downstream.

Speed downstream = u + v = (2.6 + 0.4) mph = 3 mph .

So the time taken =
`(1.1)/(3)` = 0.366 hour .