It's a simple one On January 22, 2010, Mr. Zhang, a shareholder, bought 1000 shares of a certain stock at the price of 16.32 yuan. On January 25, the price of the stock rose by 1 / 10. However, the stock market changed dramatically. On January 26, the price of the stock fell by 1 / 10. Mr. Zhang said that my stock price was the same as that on January 22. Is Mr. Zhang right? Calculation instructions

It's a simple one On January 22, 2010, Mr. Zhang, a shareholder, bought 1000 shares of a certain stock at the price of 16.32 yuan. On January 25, the price of the stock rose by 1 / 10. However, the stock market changed dramatically. On January 26, the price of the stock fell by 1 / 10. Mr. Zhang said that my stock price was the same as that on January 22. Is Mr. Zhang right? Calculation instructions

On January 25, the stock price was 16.32 × (1 + 1 / 10) = 17.952 yuan
On January 26, the stock price was 17.952 × (1-1 / 10) = 16.1568 yuan
So Mr. Zhang is not right

In order to determine the mass fraction of solute in a sodium hydroxide solution, 20 g of the sodium hydroxide solution can be fully mixed with 20 g of dilute sulfuric acid, and then copper sulfate solution is added to the solution until the reaction is complete, and 64.3 g of copper sulfate solution is consumed to obtain a colorless solution with 4.9 g of blue precipitation and 10% mass fraction. The mass fraction of solute in sodium hydroxide solution is calculated based on the above experimental data（ Keep two decimal places in the calculation process)

Let the mass of sodium hydroxide reacting with copper sulfate be x, and the mass of sodium sulfate produced be y.2naoh + CuSO4 = Cu (OH) 2 ↓ + na2so480 & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; 142x & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; 4.9g & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; &If the mass of the solution after reaction is 20g + 20g + 64.3g-4.9g = 99.4g, and the mass of sodium sulfate in the solution is 99.4g × 10% = 9.94g, then the mass of sodium sulfate formed by the reaction of sodium hydroxide with dilute sulfuric acid is 9.94g-7.1g = 2.84g. Suppose that the mass of sodium hydroxide reacted with dilute sulfuric acid is z2naoh + H2SO4 = Na2SO4 + 2h2o80 & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; &142z & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; 2.84g80z = 1422.84g & nbsp; & nbsp; Z = 1.6g mass fraction of solute in sodium hydroxide solution = 4G + 1.6g20g × 100% = 28% a: mass fraction of solute in sodium hydroxide solution is 28%

A project, a alone to do 4 days to complete, B alone to do 5 days to complete
(1) How much of the project is completed by Party A and Party B every day?
(2) After two days of cooperation between Party A and Party B, how many parts of the project are left unfinished?
(3) How many more days will it take for Party A to finish the rest after 2 days?

(1) The work efficiency of Party A is 1 / 4, that of Party B is 1 / 5, and that of Party A and Party B cooperation is 1 / 4 + 1 / 5, that is, the daily workload of their cooperation is 1 / 4 + 1 / 5 = 9 / 20
(2) 1-9/20*2=1/10
(3)
(1-2 * 1 / 4) / (1 / 4 + 1 / 5) = 10 / 9 (days)