Imanihudson
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You have jogged 5 miles from the park at a rate of r miles per hour. On your way back to the park your average speed increases by 1 mile per hour.

a. Write an expression for the time t (in hours) it takes to jog 5 miles
from the park as a function of your average speed r (in miles per hour) ___________

b. When you run back to the park, your average speed increases by 1 mph.
Write an expression representing your new speed. ___________

c. Write an expression for the time t(in hours) it takes to jog 5 miles
back to the park. ___________

d. Use your answers to parts a and c to write an expression that gives the total jogging time T (in hours) as a function of your average speed r (in miles per hour) when you are jogging away from the park. Write your answer as a single rational expression.


e. Find the total jogging time if you jogged away from the park at an average speed (r) of 4 miles per hour. Round your answer to the nearest tenth.

Respuesta :

DeanR
You have jogged 5 miles from the park at a rate of r miles per hour. On your way back to the park your average speed increases by 1 mile per hour. 

a. Write an expression for the time t (in hours) it takes to jog 5 miles
from the park as a function of your average speed r (in miles per hour) ___________

[tex]t = \dfrac 5 r[/tex]

b. When you run back to the park, your average speed increases by 1 mph.
Write an expression representing your new speed. ___________

[tex]r + 1[/tex]

c. Write an expression for the time t(in hours) it takes to jog 5 miles
back to the park. ___________

[tex]t =\dfrac 5 {r+1}[/tex]

d. Use your answers to parts a and c to write an expression that gives the total jogging time T (in hours) as a function of your average speed r (in miles per hour) when you are jogging away from the park. Write your answer as a single rational expression.
[tex]T =\dfrac 5 {r} +\dfrac 5 {r+1} = \dfrac{(5r+5)+5r}{r(r+1)}=\dfrac{10r+5}{r(r+1)}[/tex]

e. Find the total jogging time if you jogged away from the park at an average speed (r) of 4 miles per hour. Round your answer to the nearest tenth.

[tex]T = \dfrac{10r+5}{r(r+1)} = \dfrac{10(4)+5}{4(4+1)}=\dfrac 9 4 = 2.25 [/tex] hours or 135 minutes

2.3 hours rounded I suppose.


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