SOLUTION: If sally can paint a house in 4 hours, and John can paint the same house in 6 hours, how long will it take for both of them to paint the house together? I need step by step pl

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Question 393275: If sally can paint a house in 4 hours, and John can paint the same house in 6 hours, how long will it take for both of them to paint the house together?

I need step by step please i have been out of high school for 5 years and am trying to get into college. thanks

Found 3 solutions by stanbon, solver91311, Alan3354:
Answer by stanbon(75887)   (Show Source): You can put this solution on YOUR website!
If sally can paint a house in 4 hours, and John can paint the same house in 6 hours, how long will it take for both of them to paint the house together?
-------------------
Sally DATA:
time = 4 hrs/job ; rate = 1/4 job/hr
-----
John DATA:
time = 6 hrs/job ; rate = 1/6 job/hr
-----
Together DATA:
time = x hrs/job ; rate = 1/x job/hr
-----------------------------------------
Equation to solve for "x":
rate + rate = together rate
1/4 + 1/6 = 1/x
Multiply thru by 12x to get:
3x + 2x = 12
5x = 12
x = 12/5 = 2.8 hrs (time to do the job when they work together)
---
Note: 2.8 hrs = 2 hr + 0.8*60min = 2hr+48 minutes
==================================================
Cheers,
Stan H.

Answer by solver91311(24713)   (Show Source): You can put this solution on YOUR website!


If A can do a job in x time periods, then A can do of the job in 1 time period. Likewise, if B can do the same job in y time periods, then B can do of the job in 1 time period.

So, working together, they can do



of the job in 1 time period.

Therefore, they can do the whole job in:



time periods.


John

My calculator said it, I believe it, that settles it
The Out Campaign: Scarlet Letter of Atheism


Answer by Alan3354(69443)   (Show Source): You can put this solution on YOUR website!
12/5 = 2.4, not 2.8

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