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Math math math math math math math math math math math math math math math math math math math math math math math math math math math math math math math math math math math math math math math math math math math math math math math math math math math math math math math math math math math math math math What is the concentration of salt water after mixing 500 g of 70% salt water and 300 g of 50% salt water? 30 kg of 25% salt water should be diluted into 6% salt water, It is known that if the salt water is kilogram, the concentration of salt water becomes 3% after adding a certain amount of water for the first time, and 2% after adding the same amount of water for the second time? The concentration of a and B alcohol is 70% and 55% respectively. Now, to prepare 3000 grams of 65% alcohol, how many grams should be taken from each of the two kinds of alcohol? A. We know that a is one-half of the sum of the other three numbers, B is one-third of the sum of the other three numbers, and C is one-quarter of the sum of the other three numbers?
1、(500x70%+300x50%)/(500+300)=62.5%
2. Water: 30x25% / (6%) - 30 = 125-30 = 95 (kg)
3. Suppose there are 200 grams of 3% alcohol, then how much water is added into it to become 2% alcohol, 200x3% / 2% - 200 = 100 (g). Now the alcohol concentration is: 200x3% / (100 + 200 + 100) = 1.5%
4. Assuming that all alcohol is 70%, there will be more. If 3000x70% - 3000x65% = 150 (g), 55% alcohol will be 150 / (70% - 55%) = 1000 (g) and 70% alcohol will be 3000-1000 = 2000 (g)
5. According to the meaning of the question, a accounts for 1 / (1 + 2) = 1 / 3 of the total, similarly, B accounts for 1 / (1 + 3) = 1 / 4 of the total, C accounts for 1 / (1 + 4) = 1 / 5 of the total, and the sum of the four numbers of ABCD is 130 / (1-1 / 3-1 / 4-1 / 5) = 600
Number multiplication learning is equal to number, number of words, number of learning, number of words
11a*11b=1001a+110c
11ab=91a+10c
=10c
Because C > 0 and a > 0, 11b-91 > 0
Then B = 9
10 divisible (11b-91) a, 0
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