Tuesday

September 23, 2014

September 23, 2014

Posted by **Heather** on Wednesday, April 24, 2013 at 5:34pm.

14.It takes 9 hours for Isabella to rake leaves by herself,but her brother Matthew can work three times as fast.If they work together, how long will it take them to rake leaves?

Rate Time Work Done

Isabella

Matthew

- algebra -
**Melannie**, Wednesday, April 24, 2013 at 6:10pmI think the answer is 3 hours

- algebra -
**Reiny**, Wednesday, April 24, 2013 at 6:26pmIsabelle's rate = lawn/9

(Matt could do it in 3 hours)

Matt's rate = lawn/3

combined rate = lawn/9 + lawn/3 = 4lawn/9

time at combined rate = lawn/(4lawn/9))

= 9/4 hrs or 2.25 hrs or 2 hours and 15 minutes

( since "lawn" canceled, we could have just used

1/9 + 1/3 = 4/9

then time = 1/(4/9) = 9/4 = 2.25 )

**Answer this Question**

**Related Questions**

Algebra - Can you please help me with these Algebra word problems? Complete the ...

Word Problem - Martha can rake the leaves in her yard in 2 hours. Her brother ...

math - When all the leaves have fallen a girl can rake the entire yard in 4 ...

math - Ryan takes 12 minutes to rake up and bag a pile of leaves. His sister ...

algebra - amy can rake leaves in her front porch in 2hrs. Her younger sister can...

Radical and Rational exponents - Estimate how long it takes you to complete a ...

algebra - THE COMMUTER Sensible Sally has a job that is 35 miles from her home. ...

Algebra 2 word problem - just checking to see if i have this problem correct ...

5th grade math (word problems) - Can you explain how to do the following ...

Algebra - jose can complete the job in a hours, and Maria can complete the job ...