SOLUTION: isa wants to cover a 6-mile course in 1 hour by running part of the course and walking the rest. she also want to take a 5 inute water break. lisa runs at 8mi/h and walks at 3 mi/h

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Question 666802: isa wants to cover a 6-mile course in 1 hour by running part of the course and walking the rest. she also want to take a 5 inute water break. lisa runs at 8mi/h and walks at 3 mi/h. How many miles will she have to run?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
isa wants to cover a 6-mile course in 1 hour by running part of the course and walking the rest.
she also want to take a 5 minute water break.
lisa runs at 8mi/h and walks at 3 mi/h.
How many miles will she have to run?
:
Let r = no. of miles to be run
then
(6-r) = no. of miles to be walked
:
Write a time equation; time = dist/speed
Change a 5 min break to 5/60 = 1/12 hr
:
run time + break + walk time = 1 hr
r%2F8 + 1%2F12 + %28%286-r%29%29%2F3 = 1
:
multiply by 24 to clear the denominators, results:
3r + 2 + 8(6-r) = 24
:
3r + 2 + 48 - 8r = 24
3r - 8r + 50 = 24
-5r = 24 - 50
-5r = -26
r = %28-26%29%2F%28-5%29
r = +5.2 mi running
:
:
Check this, walking distance: 6 - 5.2 = .8 min
5.2%2F8 + 1%2F12 + .8%2F3 =
use a calc, it totals 1 hr