Given that Steve can paint his greenhouse in 4 hours 40 minutes minutes, working alone; his brother Phil can do the same job in 6 hours, working alone. If they work together, to the nearest minute, how long will it take them? Let Rate of Steve be S, Rate of Phil be P.
We will be using
Rate * Time = Work done formula.
Since work done is same so we will take work done as 1
Steve can paint his greenhouse in 4 hours 40 minutes minutes, working alone=> 4 hours 40mins = 4*60 + 40 mins = 280 mins
=> S * 280 = 1
=>
S = \(\frac{1}{280}\) ...(1)
Phil can do the same job in 6 hours, working alone=> 6 hours = 6*60mins = 360 mins
=> P * 360 = 1
=>
P= \(\frac{1}{360}\) ...(2)
How long will it take both of them working together to finish the work=> Combined Rate = S + P = \(\frac{1}{280}\) + \(\frac{1}{360}\) = \(\frac{1}{40*7}\) + \(\frac{1}{40*9}\)
= \(\frac{9 + 7}{40*7*9}\) = \(\frac{16}{40*7*9}\) = \(\frac{2}{315}\)
=> (S + P) * Time = 1
=> \(\frac{2}{315}\) * Time = 1
=> Time = \(\frac{315}{2}\) = 157.5 mins ~ 120 + 38 mins = 2 hours 38 minutes
So,
Answer will be AHope it helps!
Watch the following video to learn How to Solve Work Rate Problems