5 is wrong. The answer should be 7. Solve 1 + 0.8y = 0.6(4 + y) for y and get 7.
I agree with the rest of your answers.
I have collected few interesting mixture problems. I do not know the original answers to these but I solved them using my technique and would like to verify my answers with yours. I am including my answers in spoilers so that you don't see it right away
1. Mixture A is 15 percent alcohol, and mixture B is 50 percent alcohol. If the two are poured together to create a 4-gallon mixture that contains 30 percent alcohol, approximately how many gallons of mixture A are in the mixture?
2. A chemist needs to mix a 10 % acid solution with 35% acid solution to end up with 1000 milliters of a 25% acid solution. How much of each solution is needed?
SPOILER: 400, 600
3. If 3 liters of 40% orange juice and 1 liter of 50% orange juice are mixed which of the following is the percentage of orange juice in the mixture?
4. One liquid solution of 7 liters contains 40 % water. A second liquid solution of 18 liters contain 20% water. If these two solutions are mixed, what percent of the mixture is water?
5. Dr. Tik needs to make a solution that is 60% alcohol. if she has 4 liters of a solution that is 25% alcohol, how many of 80% solution will she need to add?
SPOILER: 2.5 lit
6. A mixture of 12 ounces of vinegar and oil is 40%n vinegar by weight. How many ounces of oil must be added to the mixtue to produce a new mixture that is only 25% vinegar?
SPOILER: 7.2 ounce
7. Two solutions of 90% and 97% purity are mixed resulting in 21liters of mixture of 94% purity. How much is the quantity of the first solution in the resulting mixture?
SPOILER: 9 litres
8. A mixture of 20ltrs of brandy and water contains 10% water. How much water should be added to it to increase the percentage of water to 25%?
SPOILER: 4 litrs
9. A cistern contains 50 liters of water. 5 litres of water is taken out of it adn replaced by wine. The process is repeated again. Find the proportion of wine and water in the resulting mixture.
1. Solve 0.15A + 0.5B = 1.2 and A + B = 4. We have 1.2 on the right side of the first equation because you need to get a 4 gallon mixture of 30% alcohol and 0.3*4 = 1.2.
2. Same idea, solve 0.1A + 0.35B = 250 and A + B = 1000.
3. You have 0.4*3 + 0.5*1 = 1.7 liters of orange juice in a 4 liter mixture, so 1.7/4 = 0.425.
4. Same idea as 3, you have 0.4*7 + 0.2*18 = 6.4 liters of water in a 25 liter mixture, so 6.4/25 = 0.256.
5. Solve 0.6(4+y) = 1 + 0.8y for y and get y = 7.
I'll do the rest later, have to go to a meeting.
Please post only one question per thread. Otherwise things can become pretty complicated when there are discussions on multiple questions.
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