word problem: How long would it take Rod to cut grass alone?  TOPIC_SOLVED

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word problem: How long would it take Rod to cut grass alone?

Postby kyl367 on Wed May 12, 2010 5:40 pm

Marcie can cut the grass in 3 hrs. working alone. When her younger brother Rod helps, it takes 2 hrs.
How long would it take Rod to cut grass alone?
grass/marcie alone = 3 hrs
grass/marcie and rod = 2 hrs
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  TOPIC_SOLVED

Postby stapel_eliz on Wed May 12, 2010 11:18 pm

kyl367 wrote:Marcie can cut the grass in 3 hrs. working alone. When her younger brother Rod helps, it takes 2 hrs.
How long would it take Rod to cut grass alone?

To learn how to set up and solve this sort of exercise, try here. :wink:

Once you understand the basic terms and techniques, do the standard set-up:

. . .time to complete task:
. . . . .Marcie: 3
. . . . .Rod: r
. . . . .together: 2

. . .portion completed per time unit:
. . . . .Marcie: 1/3
. . . . .Rod:
. . . . .together:

Complete the table, add the input amounts per unit time, set equal to the output amount, and solve for the variable.
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