SOLUTION: ellen and kate raced on their bicycles to the library after school. they both left school at 3:00pm and bicycled along the same path. ellen rode at a speed of 12 miles per hour and

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Question 506230: ellen and kate raced on their bicycles to the library after school. they both left school at 3:00pm and bicycled along the same path. ellen rode at a speed of 12 miles per hour and kate rode at 9 miles per hour. ellen got to the library 15 minutes before kate.
how far away is the libarary from the school?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
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ellen and kate raced on their bicycles to the library after school
ellen rode at a speed of 12 miles per hour and kate rode at 9 miles per hour. ellen got to the library 15 minutes before kate.
how far away is the libarary from the school?
:
Since we are using mph, chang 15 min to .25 hrs
:
Let d = distance, school to library
:
Write a time equation, time = dist/speed
:
K's time - E's time = .25 hrs
d%2F9 - d%2F12 = .25
multiply by 36
36*d%2F9 - 36*d%2F12 = 36(.25)
cancel the denominators, results
4d - 3d = 9
d = 9 mi to the library
:
:
Check this; find the actual travel time of each:
9/9 = 1 hr
9/12 = .75 hr
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differ .25 hrs