Question

The speed of the current in a river is 6 mph. A ferry operator who works that part of the river has a route that takes him 24 miles each way against the current and back to his dock, and he needs to make this trip in a total of 8 hours.

Given that the total time is 8 hours, write an equation that models this situation.

Answer 1

6 mph

Explanation:

Let’s call the speed of the ferry in still water v. Then, we can use the formula:

distance = rate × time

to set up two equations for the trip upriver and downriver:

24 = (v - 6) × t1

24 = (v + 6) × t2

where t1 is the time it takes to travel upriver and t2 is the time it takes to travel downriver.

We also know that the total time for the round trip is 8 hours:

t1 + t2 = 8

We can solve this system of equations by first solving for t1 and t2 in terms of v:

t1 = 24 / (v - 6)

t2 = 24 / (v + 6)

Substituting these expressions into the equation for total time gives:

24 / (v - 6) + 24 / (v + 6) = 8

Multiplying both sides by (v - 6)(v + 6) gives:

24(v + 6) + 24(v - 6) = 8(v - 6)(v + 6)

Simplifying this equation gives:

48v = 288

So v = 6.

Therefore, the speed of the ferry in still water is 6 mph.

I hope this helps! Let me know if you have any other questions.