Question

A motorboat can go 16 miles downstream on a river in 20 minutes. It takes 30 minutes for this boat to go back upstream the same 16 miles. Let x = the speed of the boat. Let y = the speed of the current. a. Write an equation for the motion of the motorboat downstream. b. Write an equation for the motion of the motorboat upstream. c. Find the speed of the current.

Answer 1

A) d = 48t, d in miles, t in hours

B)d = 32t, d in miles, t in hours

C)y = 8 mph

Explanation:

16 miles in 20 mins = 48 mph

16 miles in 30 mins = 32 mph

The boat speed is the average = (48 + 32)/2 = 40 mph

The current is the difference = 8 mph