A boat can travel 30 miles upstream in the same amount of time you can travel 50 miles Downstream. If the speed of the current is 4 miles per hour, find the speed of the boat in still water.

Speed, S = Distance (d) / Time (t) = > S = d/t = > t = d/S

Let the speed of boat in still water be x mph

Resulting speed upstream = x-4 mph for a distance of 30 miles

Resulting speed downstream = x-4 mph for a distance of 50 miles

Time taken in both distances is equal.

Therefore,

30 / (x-4) = 50 / (x+4) = > 30 (x+4) = 50 (x-4) = > 30x+120 = 50x-200 = > 120+200 = (50-30) x = > 20x = 320 = > x=320/20 = 16 mph

The speed of boat in still water is 16 mph.

The correct answer is 16mph.