A biker travels the 120 mi from New York , NY to Wilmington, DE in 8 hours. A bus, a truck, and a rider on a horse take the same route as the biker. At what speed does each of them travel if it takes them 2 hours, 2.5 hours, and 18.75 hours respectively to reach Wilmington? Do the speed and the time vary directly or inversely proportional when the same distance is traveled? Explain why.

First, remember the relation:

Distance = Speed*Time.

We know that the distance is 120mi.

A) For the biker we know that:

Time  = 8hours.

Speed = Distance/Time = 120mi/8h = 15 mi/h.

B) For the bus we know that:

Time = 2 hours.

Speed = Distance/Time = 120mi/2h = 60 mi/h.

C) For the truck we know that:

Time = 2.5 hours.

Speed = Distance/Time = 120mi/2.5h = 48 mi/h.

D) For the rider on a horse we know that:

Time = 18.75 hours.

Speed = Distance/Time = 120mi/18.75h = 6.4 mi/h.

E) The equation for the speed is:

Speed = Distance/Time.

You can see that time is in the denominator, this means that if for a fixed distance, the time increases, then the denominator increases, which would imply that the speed decreases.

Then the speed is inversely proportional to the time when the distance is fixed.

or

step-by-step explanation:

we need to solve for 'x' the following equation:  

we have that:

⇒

⇒ ⇒

factorizing, we get that:

  ⇒

then, the solutions are: or

nothing extraneous has been found!

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step-by-step explanation:

(sorry i'm not typing it again just read the other two explanation sections i just typed it'll be the same.)