<PRE><B>Question 203843</B>
When 6 students show up for the Swift River Cleanup Day, they can pick up
 all of the bottles and trash on their section of the riverfront in 2 1/2 hr.
 If 9 students show up, how long will the same cleanup take?
:
Let t = time required using 9 students
;
You can solve this using man-hrs, given:
6 * 2.5 = 15 man-hrs required to do the job
Then
9t = 15
t = {{{15/9}}}
t = 1{{{2/3}}} hrs if 9 students work
:

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