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The water in children's body accounts for about 45% of their body weight. Xiaoming has 28 kg of water in his body. How many kg is Xiaoming's weight?
A: Xiao Ming weighs 35 kg
Xiao Ming's weight is 4 / 5 of Xiao Lin's and Xiao Gang's is 4 / 5 of Xiao Ming's
A Xiaogang is the heaviest
B Xiaoming is the lightest
C Xiaolin is the heaviest
D Kobayashi is the lightest
Let Xiaolin weigh 25X, then Xiaoming's weight is 20x, Xiaogang's weight is 16x, obviously 25X is greater than 20x and greater than 16x, so Xiaolin is the heaviest, Xiaogang is the lightest, choose C
Xiao Cong and Xiao Ming have some glass balls. Xiao Cong says to Xiao Ming, "my glass balls are twice as big as yours." Xiao Ming says to Xiao Cong, "if you give me three, we'll have the same number." how many glass balls do they have?
According to the stem analysis, the number of Xiaoming's glass balls is 3 × 2 = 6, XiaoCong's glass balls is 6 × 2 = 12, a: XiaoCong has 12, Xiaoming has 6
How to measure the open circuit voltage and short circuit current of an active two terminal network and under what circumstances can they not be measured directly?
The open circuit voltage at both ends of the power supply can be directly measured with a voltmeter in parallel with the battery
The short-circuit current at both ends of the power supply is generally not measured directly, because the current is too large, it is easy to damage the ammeter
1. Xiao Ming reads a book. The ratio of the number of pages read to the number of pages not read is 1:5. If he reads another 30 pages, the ratio of the number of pages read to the number of pages not read is 3:5. How many pages is the book?
2. There are 160 sheep and cattle in a farm. One tenth of the sheep are sold at a time, and another 30 cattle are bought. At this time, the number of sheep and cattle is equal. How many sheep and cattle are there?
3. For a barrel of gasoline, the weight of the barrel is 8% of the weight of the gasoline. After 48 kg of gasoline is poured out, the weight of the oil is equivalent to 1 / 2 of the weight of the barrel. How many kg of the oil barrel and the original gasoline?
4. A car arrives in 6 hours from city a to city B, and it takes only 5 hours to get the distance between city a and city B?
5. There is a pile of candy, of which milk candy accounts for 45%. After adding 16 pieces of fruit candy, milk candy only accounts for 25%. How many pieces of milk candy are there in this pile of candy?
Wrong number 4
A car arrived in six hours from city a to city B. when it returned, it sped up. It was 8 kilometers more per hour than before. It took only five hours to find the distance between city a and city B?
Question 1: let the number of pages read be x and the number of pages unread be y
The formula is X: y = 1:5
(x+30):(y-30)=3:5
According to the fact that the product of introversion is equal to the product of extroversion
5x=y
5x-3y=-240
The solution is x = 24, y = 120
Total pages = x + y = 24 + 120 = 144
Question 2: suppose there are x sheep and Y cattle
Series of equations x + y = 160
x-1/10x=y+30
We get x = 100, y = 60
The third question: set oil barrel x kg, gasoline y kg
Set of equations x = 8% Y
y-48=1/2x
We get x = 4, y = 50
Set the speed from city a to city B as X km / h
Then the speed of coming back is (x + 8) km / h
There is 6x = (x + 8) * 5, and the solution is x = 40
Question 5: let the total number of original sugar be x, and the number of milk candy be y
Set of equations y = 45% X
y=25%(x+16）
We get x = 20, y = 9
I've tried my best. I hope you can understand
How long can I use 12 V 120 a battery to change from 220 V to 1000 W electric appliance? How long can I use 24 V 240 a
12v120a battery can be used for about 3 hours. Can your inverter be used for 24 V or in parallel? 240 a battery can be used for about 1 hour more
As shown in the figure, the parabola y = - x2 + BX + C intersects with the straight line y = 2 / 1X + 2 at two points c and D, where point C is on the y-axis, the coordinate of point D is (3,7 / 2), point P is a moving point on the parabola on the right side of the y-axis, passing through point P as PE, perpendicular to the x-axis and at point E, intersecting CD and point F
(1) If the abscissa of point P is m, what is the value of M, then the quadrilateral with vertices o, C, P and F is a parallelogram? Why?
(2) If there is a point P and the angle PCF is 45 °, write the coordinates of the corresponding point P directly
The process is as shown in the figure. If you agree with my answer, please click "adopt as a satisfactory answer". I wish you progress in your study!
What is the Avogadro constant? What is the specific value of mole? What can it be used to measure?
(1) Avogadro's constant (symbol: NA) is an important constant in physics and chemistry. Its value is 6.02 × 10 ^ 23 or 6.022 × 10 ^ 23 in general calculation. Its formal definition is the number of carbon 12 atoms contained in 0.012kg carbon 12
(2) Mole, formerly known as mole or atom, is one of the seven basic units of the international system of units. It represents the quantity of matter (the quantity of matter represents the physical quantity of a certain number of particles, which is a proper noun. The object of study can only be particles). The quantity of matter is the physical quantity used to measure the number of microscopic particles of matter. The symbol is n, and the unit of the quantity of matter is mole (abbreviated as Mo), The symbol is mol). Every 1mol of any substance contains particles with Avogadro constant (about 6.02 × 10 ^ 23). When using mole, the basic particles should be specified, which can be atoms, molecules, ions, atomic clusters, electrons, protons, neutrons and other particles, or a specific combination of these particles, The number of particles contained in 1mol particle group is the same as that contained in 0.012kg 12C (C 12), that is, the number of structural particles contained in a mole of any substance is equal to that contained in 0.012kg 12C (C 12), that is, 6.0221367x10 ^ 23 structural particles, For example, M = 2.02x10-3kg of hydrogen, M = 2.02x10-3kg, f = m, and the ratio of m to μ is called the amount of the substance (also known as the number of moles), = m μ. For example, M = 4.04x10-3kg of hydrogen, h2 = 2. The volume of one mole of substance, VM, is called the molar volume. The molar volume of gas depends on temperature and pressure, The relationship between the molar volumes of solid and liquid substances and temperature and pressure is small
(3) The Avogadro constant is closely related to the quantity of matter. As the basic unit of the international system of units, mole is defined as the Avogadro constant (NA). The basic unit can be any kind of matter (such as molecule, atom or ion)
What is off form calculation? Solution, thank you!
Out of form calculation, that is, recursive equation calculation, is the calculation that completely writes out the calculation process, that is, the calculation that breaks away from the vertical formula. Formula calculation, that is, the calculation that completely writes out the calculation process, that is, the calculation that breaks away from the vertical formula. In the calculation of mixed operation, usually one formula is calculated step by step (the equal sign cannot be written on the original formula), Write out the process of each step. Generally speaking, the equal sign should go forward, not aligned with the first line. That is to say, leave the original formula
The filament resistance of a small bulb is 10 ohm, and the voltage is 3V when it works normally. If it is directly connected to the power supply with the voltage of 4.5V, the small bulb can emit light normally
In the morning of normal lighting, the current of the lamp is 0.3A. So just connect a resistor R = (4.5-3) / 0.3 = 5 in series,
RELATED INFORMATIONS
- 1. Xiao Li and Xiao Gang are 900 meters away from home. They start from home at the same time. Xiao Li walks 60 meters every minute and Xiao Gang walks 90 meters every minute. A few minutes later, they meet?
- 2. Xiaohong and Xiaoqiang start from home at the same time. Xiaohong walks 52 meters per minute and Xiaoqiang 70 meters per minute. They meet at a on the way. If Xiaohong starts 4 minutes ahead of schedule and Xiaoqiang walks 90 meters per minute, they still meet at a. how many meters are Xiaohong and Xiaoqiang's homes apart?
- 3. Xiaoming starts from a at 8 a.m. and goes to B at 20 kilometers per hour. 15 minutes later, Xiaogang starts from a and goes to B at 16 kilometers per hour In B, Xiao Ming takes a 60 minute rest in B and then returns to A. on the way back, he meets Xiao Gang from A. at this time, they are 2 kilometers away from B. find the distance between a and B
- 4. Xiaoming starts from a at 8 a.m. and goes to B at 20 kilometers per hour. 15 minutes later, Xiaogang starts from a and goes to B at 6 kilometers per hour In B, Xiao Ming takes a 60 minute rest in B and then returns to A. on the way back, he meets Xiao Gang who starts from A. at this time, they are 2 kilometers away from B. find the distance between a and B
- 5. Xiao Gang used to have some pictures. He took out half of them and gave them to his younger brother. Later he bought 18 more. At this time, there were 47 pictures. How many pictures did he have?
- 6. Xiaogang and Xiaoqiang practice running on the 400 meter circular track. Their speed is 200 meters per minute and 160 meters per minute respectively
- 7. Xiao Gang is 140 cm tall. Xiao Gang is 27 times higher than Xiao Ming. How many cm is Xiao Ming?
- 8. Xiaoming's height is 112 cm higher than Xiaojun's, and Xiaojun's height is 12 cm shorter than Xiaoming's______ ．
- 9. Xiaoming is 142 cm tall, a cm shorter than Xiaohua, and Xiaohua is () cm tall
- 10. Three students are taller. As a result, Xiaojun is 1 / 12 meters shorter than Xiaoming and 1 / 20 meters higher than Xiaofang. How many meters is the tallest one higher than the shortest one
- 11. Xiao Ming and Xiao Gang's money is 0.75 yuan more than Xiao Ming's and 1.48 yuan more than Xiao Gang's There should be a formula
- 12. Xiao Ming and xiao gang went to the boutique stationery store to buy the same kind of pens and exercise books. The following is their dialogue with the salesman: Xiao Gang: auntie, how much do I need to buy three pens and two exercise books? Xiao Ming: auntie, I have 21 yuan with me. I want to buy a pen. I want to buy exercise books for the rest. How many do you think I can buy? Salesperson: let me calculate. A pen is twice as much as an exercise book, and it costs more than 1 yuan. After buying a pen, you can also buy several exercise books. Students, can you fill in the blanks? Give reasons
- 13. Xiao Ming's glass balls are four times as big as Xiao Gang's. Xiao Ming gives Xiao Gang three, and they have the same number. How many glass balls do they have
- 14. Xiao Gang, Xiao Li and Xiao Ming each have some pictures. The ratio of the three is 8:5:2. Xiao Li has 30 pictures. How many pictures do Xiao Gang and Xiao Ming have?
- 15. Xiaohua plans to read a 120 page story book in [7 days] a week. On the first day, he reads 1 / 5 of the book, and the rest 16 pages a day. Can he finish it in the original time
- 16. There are only three story books and five undergraduate teaching books in the bookcase. How many books should we take out at least to ensure that we take out two identical books at a time?
- 17. There are five story books and nine science and technology books mixed in the bookcase. Make sure you can take out at least one science and technology book and at least how many books
- 18. (1 / 2) Xiao Gang read a story book. He read 56 pages every day. After 4 days, he happened to read 8 / 11 of the whole book. How many pages are there in this book? How many pages are left (1 / 2) Xiao Gang read a story book. He read 56 pages a day. After 4 days, he happened to read 8 / 11 of the whole book. How many pages are there in this book? How many pages are there left? (don't make equations, just send me the formulas
- 19. Xiao Hong read a story book. On the first day, she read 45 pages. On the second day, she read 25 pages of the whole book. On the second day, she read 20% more pages than on the first day. How many pages are there in this book?
- 20. Xiao Gang read a story book. On the first day, he read 72% of the whole book. On the second day, he read 13% of the whole book. There are 60 pages left?