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Title: John is mixing a saline solution. He has 4 gallons of a 70%solution........? Post by: oakhan on Sep 14, 2012 John is mixing a saline solution. He has 4 gallons of a 70%solution. How many gallons of a 32% solution does he need to created a 58% saline solution?
I have another question. Sally and Paul can paint a room in 6 hours. Paul working alone can paint the room 2 hours quicker than sally. How long does it take each of them to paint the room working alone? Title: John is mixing a saline solution. He has 4 gallons of a 70%solution........? Post by: tonyekwe on Sep 14, 2012 1) Assuming the percentage solution is volume/volume (otherwise is a very challenging problem)
Initial amount of salt 4*.7 = 2.8 gal salt Let V = volume added of the 32% solution (2.8 + 0.32V)/(4 + V) = 0.58 (4 + V)0.58 = 2.8 + 0.32V 0.26V = 0.48 V = 1.85 gal 2) Let S = Sally speed P = Paul speed A = Total area painted t = time to finish painting t = A/(S + P) A/(S + P) = 6 2A/P = A/S P/A = 2S/A 1/6 = P/A + S/A 1/6 = P/A + P/2A P/A = 1/9 It takes Paul 9 hours to paint it by himself S/A = 1/18 It takes Sally 18 hours to paint it by herself |