Example of Practical Problems and Inverse Proportional Function in Grade Eight Mathematics [ppt Courseware for Grade Two Mathematics]: 17.2 Practical Problems and Inverse Proportional Function (III) Problems 1: The volume V(m3) of a certain mass of carbon dioxide gas is an inverse proportional function of the density ρ(kg/m3). Please find the equivalent density ρ = 1.60 according to the known conditions in the figure below. 900 Question 2: The annual electricity price of a certain ground is 0.8 yuan, and the annual electricity consumption is 65.438+0 billion kWh. It is planned to adjust the electricity price to 0.55 ~ 0.75 yuan this year. According to the calculation, if the electricity price is adjusted to X yuan, the newly-increased electricity consumption y (1 100 million kwh) is inversely proportional to (X-0.4) yuan. When x=0.65 yuan, Y = (1) finds the functional relationship between y and X; (2) If the cost per kWh is 0.3 yuan, when the electricity price is adjusted to how much yuan, part of the revenue of electricity this year will increase by 20% compared with the previous year? [Income = electricity consumption × (actual electricity price-cost price)] Question 3: A food group company has 200kg of salt water with a salt content of 30%, and now it needs to evaporate some water. If the brine concentration of xkg water after evaporation is Y, can you write the functional relationship between Y and X? And point out the range of independent variables. Question 4: To make a product, you need to heat the material to 60℃ before you can operate it. It is understood that when the material is heated, the temperature y℃ is linearly related to the time x(min). When the heating operation is stopped, the temperature y℃ is inversely proportional to the time x(5min). As shown in the figure, it is known that the temperature of the material before operation and processing is 15℃, and the temperature reaches 60℃ after heating for 5 minutes. (1) The functional relationship between y and x when the material is heated and stopped is obtained. (2) According to the process requirements, when the material temperature is lower than 65438 05℃, the operation must be stopped. So how long did it take * * * from the start of heating to the stop of operation? Question 5: Haimen Ji 'an Tunnel is the largest tunnel in China.