SOLUTION: A girl can rake the entire yard in 8 hours. When a boy does it alone, it takes him 9 hours. How long would it take them to rake the yard together? Round to the nearest minute.

Algebra ->  Rate-of-work-word-problems -> SOLUTION: A girl can rake the entire yard in 8 hours. When a boy does it alone, it takes him 9 hours. How long would it take them to rake the yard together? Round to the nearest minute.      Log On


   

Question 963127: A girl can rake the entire yard in 8 hours. When a boy does it alone, it takes him 9 hours. How long would it take them to rake the yard together? Round to the nearest minute.
Found 2 solutions by amarjeeth123, macston:
Answer by amarjeeth123(570) About Me  (Show Source):
You can put this solution on YOUR website!
A girl can rake the entire yard in 8 hours.
In 1 hour she can rake 1/8th of the yard.
When a boy does it alone, it takes him 9 hours.
In 1 hour he can rake 1/9th of the yard.
When they work together in 1 hour they can rake (1/8+1/9) of the yard.
In 1 hour they can rake 17/72 of the yard.
Total time taken=72/17hours=254 minutes(approx.)

Answer by macston(5194) About Me  (Show Source):
You can put this solution on YOUR website!
Girl=1yard/480min=1/480 yard/min=9/4320 yd/min
Boy=1 yard/540 min=1/540 yard/min=8/4320 yd/min
Together=9/4320 yd/min + 8/4320 yd/min=17/4320 yd min
1 yard/ (17/4320 yd/min)=254 minutes
ANSWER: Together they can rake the yard in 254 minutes.