Question 99921
You are running water into a laundry sink to get a mixture that is one-half hot water and one-half cold water. The hot water flows more slowly, at a rate of 7.8 liters per minute, so you turn it on first. Two minutes later, you also turn on the cold water which flows at a rate of 12.3 liters per minute. You want to know how long to wait before turning the two faucets off.
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a. Let t represent the number of minutes the hot water is on. Write a variable expression for the amount of time the cold water is on.
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Cold water time = (t - 2)
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b. Write an equation that models the situation. Then solve the equation.
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cold water amt = hot water amt
12.3(t-2) = 7.8t
12.3t - 24.6 = 7.8t
12.3t - 7.8t = + 24.6
4.5t = 24.6
t = 24.6/4.5
t = 5.467 min turn off both faucets
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Check: 
Cold water is on for 5.467 - 2 = 3.467
Check for equal amts
5.467 * 7.8 = 42.6 liters
3.467 * 12.3 = 42.6 liters also confirms our solution
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c. Interpret your solution. If the solution is a decimal, decide what form of the number is most appropriate. Explain your choice

Since the flow rate is given in decimals, use decimals.
I'll let you interpret the solution.