what is the average speed of a boat in stillw ater if i tmakes a 280 mi trip downriver but takes an extra eight hr to return upriver against a 2 mi/hr current

Respuesta :

Answer:

To find the average speed of the boat in still water, we can use the concept of relative speed.

Let's denote the speed of the boat in still water as "S" and the speed of the current as "C."

When the boat travels downriver, its effective speed is the sum of its speed in still water and the speed of the current, so it travels at (S + C) miles per hour.

When the boat travels upriver, its effective speed is the difference between its speed in still water and the speed of the current, so it travels at (S - C) miles per hour.

We know that the boat makes a 280-mile trip downriver but takes an extra 8 hours to return upriver against a 2 mi/hr current.

Using the formula distance = speed * time, we can set up the following two equations:

280 = (S + 2) * t_downriver 280 = (S - 2) * (t_upriver + 8)

Solving these two equations will give us the values of S (speed of the boat in still water) and t_upriver (time taken to travel upriver).

Once we have those values, we can find the average speed of the boat in still water by using the formula:

Average speed in still water = (Speed downriver + Speed upriver) / 2

I can help you with the calculations if you provide the values for t_downriver and t_upriver, or I can solve the equations directly if you'd like.

Answer: The speed of the boat in still water is 12 mi/hr.

Step-by-step explanation:

Let the speed of the boat in still water be ss mi/hr.Downriver speed = s+2s+2 mi/hr (due to the current)

Upriver speed = s−2s−2 mi/hr (against the current)Given that the boat takes 8 hours longer to return upriver, we can set up the equation:280 mis+2 mi/hr−280 mis−2 mi/hr=8 hrs+2 mi/hr280 mi​−s−2 mi/hr280 mi​=8 hrMultiplying both sides by (s+2)(s−2)(s+2)(s−2) to clear the denominators:280(s−2)−280(s+2)=8(s+2)(s−2)280(s−2)−280(s+2)=8(s+2)(s−2)Simplify:280s−560−280s+560=8(s2−4)280s−560−280s+560=8(s2−4)1120=8s2−321120=8s2−328s2=11528s2=1152s2=144s2=144s=12s=12

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