In the spring of 2009, influenza A (H1N1) virus spread in the United States and some other countries, and human beings had another battle with the virus. Peracetic acid is one of the disinfectants that can effectively kill avian influenza virus. 0.2% Peracetic acid solution is often used for air and ground disinfection. A farm needs to prepare 50 kg of 0.2% Peracetic acid disinfection solution, How many kilograms of 10% Peracetic acid solution is needed? How many kilograms of water should be added? Answer before 9 o'clock

In the spring of 2009, influenza A (H1N1) virus spread in the United States and some other countries, and human beings had another battle with the virus. Peracetic acid is one of the disinfectants that can effectively kill avian influenza virus. 0.2% Peracetic acid solution is often used for air and ground disinfection. A farm needs to prepare 50 kg of 0.2% Peracetic acid disinfection solution, How many kilograms of 10% Peracetic acid solution is needed? How many kilograms of water should be added? Answer before 9 o'clock

In the spring of 2009, influenza A (H1N1) virus spread in the United States and some other countries, and human beings had another battle with the virus. Peracetic acid is one of the effective disinfectants to kill avian influenza virus. 0.2% Peracetic acid solution is often used for air and ground disinfection

Scientific simple calculation problems
The length, width and height of a classroom are 9 meters, 6 meters and 3 meters respectively. How many kg is the air quality of this classroom? (pair = 1.29 kg / m3)

Mass = volume * density = length * width * height * density = 9m * 6m * 3M * 1.29kg/m3 = 208.98kg/m3

Solve 10 application problems!
There are 25 boys and 20 girls in class 6. 1. How many percent more boys than girls? 2. How many percent less girls than boys?
2. A road repair team built a road, 50% in the first quarter, 800 meters in the second quarter, and 30% of the total length was not repaired. How long is the road?
3. There are 15 tons of steel in the warehouse, 20% of the total amount is used in the first time, and 1:2 tons is used in the second time. How many tons are used in the two times?
4. To grind wheat into flour, 15% of bran is needed. To grind 1700kg of flour, how many kg of wheat is needed?
5. The output value of a factory last year was 1.58 million yuan, 200000 yuan less than this year. How much is the output value this year?
6. A basket of Chinese cabbage weighs 94.5kg. After half of it is taken out, there is 48.5kg left in the basket. How many kg does the basket weigh?
7. It takes 1:5 hours for students to do experiments, 3:10 hours for teachers to give lectures, and the rest of the time for students to do homework. Given that each class has 40 minutes, how many hours do students do their homework?
8. Mr. Wang's family used 160 kilowatt hours of electricity in April, but it used more electricity in May than in April. 1: less electricity in June than in May. 1: how much electricity in June?
9. Xiaoming bought a dictionary and a composition selection in the bookstore. It is known that the dictionary is 1.8 yuan more expensive than the dictionary. The price of composition selection is 2:5 of the dictionary. How much is the price of the dictionary?
10. The cocoon output of sericulture professional users last year was 60 tons, and this year is 30% higher than that of last year. How many tons of spring cocoon will be produced this year?

1. (1) (25-20) / 20 = 0.25 = 25% (2) (25-20) / 25 = 0.2 = 20% 2, 1-50% - 30% = 20% 800 / 20% = 4000 (m) 3, 15 * 20% = 3 (T) 3 + 1 / 2 = 3 and 1 / 2 (T) 4, 1-15% = 85% 1700 / 85% = 2000 (kg) 5, 158 + 20 = 178 (ten thousand yuan) 6, 94.5-48.5 = 46 (kg) 46 * 2 =