explain all parts of the questions

The conceptual level ERD using Chen's notation showing the entities and their attributes, and the relationships and their cardinalities, attributes, and optionality (ordinality) b) The logical level ERD using Crow's Foot notation should include the entities, their attributes, the PKs, the mapped FKs and relationships and their cardinalities, attributes, and optionality. All Many-to-Many relationships (if there is any) should be mapped into a new table (associative entity) and the attributes, the FKs and the PK of the associative entity must be included in the new table. c) Add any text you would like to include to justify or explain any assumptions you made about entities not mentioned in the system description.

Car management and usage tracking database system: A company wants to build a database system that manages and track the usage and maintenance of a fleet of cars it owns. Each car has a unique Id number, VIN, make, mode, year, and license plate number. The company keeps record of important dates related to each car, like registration and insurance renewal dates and regular maintenance date. Each car may or may not have maintenance records, and each maintenance record should include the type of maintenance (regular, casual, emergency, etc. ), the date, the location, the cost of the maintenance, and the employee who approves it. The company has multiple employees who may or may not use any of the company's cars, so the Page 2 of 2 company wants to keep track of who uses which car, when, and for how long (i.e., start of use and end of use time and date). The company also wants to keep record for any accident or law violation tickets associated with any of its cars and the employee involved in them. The typical accident/violation record includes the date and time of the accident/violation, its type (violation, accident), its location, a short description, the employee, the car involved, and the total cost. The system will allow the company to get information and answer queries about its cars like, which car is maintenance due this month, or who are the employees who used certain car in a specific period of time, how many times a specific employee has involved in a car accident or law violation, and so on.

All problems are due in class next week. Be complete and succinct. Feel free to work together, but submit your own answers. 1. Recall that the Law of Demand states that demand curves are always downward-sloping. That is, people want to buy more of some good when its price is lower. a. Why is a firm's short-run demand for labor downward-sloping? b. Is the firm's long-run demand for labor necessarily downward-sloping? Explain, using the substitution and scale effects. 2. Most industrial farms hire migrant workers, so the market for such workers is reasonably taken to be perfectly competitive. Suppose that all farms individually have a short-run elasticity of labor demand of -0.5. In other words, if the wages of migrant workers in a local labor market rose by 10% (say, because many of those workers decided to work at a recently-opened nearby factory), the farms in the area would want to hire 5% fewer workers. Nevertheless, it is true that if the wages of migrant workers rose by 10% everywhere, employment of migrant workers would fall by less than 5 percent in the short run. a. Explain why the reduction in employment would be less than 5 percent in the latter case. (Hint: Read pp. 141-143 of your textbook carefully (pp. 140-142 if you have the old edition).) b. In light of the short-run elasticity of demand for migrant workers, how easy do you think it would be for the industrial farms to replace the workers' efforts by using the existing stock of farm machinery more intensely? c. If the nationwide 10% wage increase were permanent, would the employment of migrant workers fall more in the short run or in the long run? Why? 3. The HRB Corporation is the world's only manufacturer of air filters for Zamboni engines. Last year, HRB charged $20 per filter and sold 1 million of them, and it paid all of its production workers $10 per hour. This year, something happened at HRB headquarters (not announced to the public) that caused HRB to lower its price to $18 per filter. (HRB is still a profit-maximizing company.) This enabled HRB to sell 1.2 million filters. Its workers all continue to earn $10 per hour. a. What is the elasticity of demand for Zamboni air filters? b. How much additional revenue does HRB earn if it sells one more air filter this year? How much additional revenue would HRB have earned if it sold one more air filter last year? c. How much are HRB's employees paid relative to the value they create? (That is, what is the ratio of the wage to the value of the worker's marginal product (price x MP_)?) d. What was the workers' marginal product last year? What is it this year? e. Suppose you are considering only two explanations for the increase in HRB's output: (1) HRB invested in better equipment and kept the same number of workers, or (2) HRB hired more workers to use its existing equipment. Given your observations above, which makes more sense? Why? Problem Set 5: Personnel Economics Economics 415 All problems are due at the next class meeting. Be complete and succinct. Feel free to work together, but submit your own answers. 1. In class we discussed several compensation schemes that employers may use to motivate workers. a. "Pay for performance" schemes may take several forms. One is a piece rate scheme, in which there is an explicit mathematical formula that translates workers' output into pay. (For example, a worker might be paid $5 per unit of out put he or she produces.) A second scheme awards workers a year-end bonus that depends on their annual performance review. Question: All else equal, would Caucasian or African-American workers have a stronger preference for the piece rate relative to the bonus system? Why? b. Women are more likely than men to hold jobs that pay workers a piece rate, but less likely to hold jobs that promise workers raises if they perform well. Why might that be? (Hint: This is not about discrimination.)All problems are due in class next week. Be complete and succinct. Feel free to work together, but submit your own answers. 1. Recall that the Law of Demand states that demand curves are always downward-sloping. That is, people want to buy more of some good when its price is lower. a. Why is a firm's short-run demand for labor downward-sloping? b. Is the firm's long-run demand for labor necessarily downward-sloping? Explain, using the substitution and scale effects. 2. Most industrial farms hire migrant workers, so the market for such workers is reasonably taken to be perfectly competitive. Suppose that all farms individually have a short-run elasticity of labor demand of -0.5. In other words, if the wages of migrant workers in a local labor market rose by 10% (say, because many of those workers decided to work at a recently-opened nearby factory), the farms in the area would want to hire 5% fewer workers. Nevertheless, it is true that if the wages of migrant workers rose by 10% everywhere, employment of migrant workers would fall by less than 5 percent in the short run. a. Explain why the reduction in employment would be less than 5 percent in the latter case. (Hint: Read pp. 141-143 of your textbook carefully (pp. 140-142 if you have the old edition).) b. In light of the short-run elasticity of demand for migrant workers, how easy do you think it would be for the industrial farms to replace the workers' efforts by using the existing stock of farm machinery more intensely? c. If the nationwide 10% wage increase were permanent, would the employment of migrant workers fall more in the short run or in the long run? Why? 3. The HRB Corporation is the world's only manufacturer of air filters for Zamboni engines. Last year, HRB charged $20 per filter and sold 1 million of them, and it paid all of its production workers $10 per hour. This year, something happened at HRB headquarters (not announced to the public) that caused HRB to lower its price to $18 per filter. (HRB is still a profit-maximizing company.) This enabled HRB to sell 1.2 million filters. Its workers all continue to earn $10 per hour. a. What is the elasticity of demand for Zamboni air filters? b. How much additional revenue does HRB earn if it sells one more air filter this year? How much additional revenue would HRB have earned if it sold one more air filter last year? c. How much are HRB's employees paid relative to the value they create? (That is, what is the ratio of the wage to the value of the worker's marginal product (price x MP_)?) d. What was the workers' marginal product last year? What is it this year? e. Suppose you are considering only two explanations for the increase in HRB's output: (1) HRB invested in better equipment and kept the same number of workers, or (2) HRB hired more workers to use its existing equipment. Given your observations above, which makes more sense? Why? Problem Set 5: Personnel Economics Economics 415 All problems are due at the next class meeting. Be complete and succinct. Feel free to work together, but submit your own answers. 1. In class we discussed several compensation schemes that employers may use to motivate workers. a. "Pay for performance" schemes may take several forms. One is a piece rate scheme, in which there is an explicit mathematical formula that translates workers' output into pay. (For example, a worker might be paid $5 per unit of out put he or she produces.) A second scheme awards workers a year-end bonus that depends on their annual performance review. Question: All else equal, would Caucasian or African-American workers have a stronger preference for the piece rate relative to the bonus system? Why? b. Women are more likely than men to hold jobs that pay workers a piece rate, but less likely to hold jobs that promise workers raises if they perform well. Why might that be? (Hint: This is not about discrimination.)1. (36 points) Two firms, A and B, are competing in the production of a homogenous good. The good's marginal cost for both firms is equal, MC = $25. Assuming linear reaction functions, describe what would happen to output and price in each of the following situations if the firms are in (i) collusive equilibrium, (ii) Cournot equilibrium, (iii) Bertrand equilibrium. (a) (4 points for each of (i)-(iii)) The demand curve shifts to the left. (b) (4 points for each of (i)-(nii)) Because it invents a new and improved machine, the marginal cost at firm B decreases to $20. (c) (4 points for each of (i)-(ii)) Costs in the entire industry increase due to an increase in wages. Problem 1 by MIT OpenCourse Ware. 2. Problem removed due to copyright restrictions. This content is presented in audio form in the Solution Video for Problem Set 8, Problem 2. 3. (28 points) Suppose a perfectly competitive labor market has a demand curve of [ = 120 - 2w and a supply curve of IS = Sw, where w is the wage rate is dollars and & is the quantity of labor in person-hours. (a) (2 points) What are the equilibrium values of the wage and employment? (b) (4 points) Suppose the government imposed a minimum wage of $14 per hour. Now what are the equilibrium values of the wage and employment? (e) (8 points) Repeat part (a), assuming now that the market is a monopsony. (d) (8 points) Repeat part (b), assuming now that the market is a monopsony. (e) (6 points) Does the imposition of the minimum wage decrease employment here under perfect competition? What about under monopsony? Give a brief intuitive explanation for your answer and why it may be different under the two different market structures. Problem 3 courtesy of William Wheaton. Used with permission. 4. (11 points) Suppose you face the following lottery. You can earn 1 of 3 possible grades in this class: an "A", a "C", or an "F, with the following probabilities: TA = 10' TO = T 10' TF = 10 Your current wealth (w) is $400. If you receive an "A", you gain (e.g. I pay you) $500. However, if you get an "F" , you lose (e-g. you pay me) $300. If you receive a "C", you DO NOT GAIN OR LOSE anything. Assume your utility function, defined over wealth, is U(w) = v(w). (a) (6 points) What is your expected utility (EU)? [Hint: be sure to calculate your total wealth in each "state".] (b) (5 points) What is the certainty equivalent level of wealth (w*), that is, the guaranteed payoff at which a person is "indifferent" between accepting the guaranteed payoff and their expected utility from (a)?1. (25 points) For each of the following scenarios, use a supply and demand diagram to illustrate the effect of the given shock on the equilibrium price and quantity in the specified competitive market. Explain whether there is a shift in the demand curve, the supply curve, or neither. (a) (5 points) An unexpected temporary heat wave hits the East Coast. Show the effect in the ice cream market in New England. (b) (5 points) The government introduces a tax on ice cream which is paid by producers. What is the effect in the ice cream market? (c) (5 points) China and Mexico are major producers of textiles. Workers in Mexico decide to go on strike. Show the effect on the market for Mexican textiles. (d) (5 points) Show the effect of the situation described in (c) on the market for Chinese textiles. (e) (5 points) Suppose the government imposes a price cap on bottled water. Show the effect in the bottled water market. Problem 1 courtesy of William Wheaton. Used with permission. 2. (20 points) For each of the following pairs of goods, identify which one you would expect to have more own-price elastic demand. Please explain your reasoning (a) (5 points) Computers (generally) vs. Apple MacBook Pro laptops. (b) (5 points) Stereo headphones (generally) vs. hearing aids. For each of the following goods, identify whether you would expect demand to be more (own-price) elastic in the short run or the long run. As above, please briefly explain your reasoning. (e) (5 points) Retail gasoline in the suburbs of Chicago. (d) (5 points) Air conditioning units in Miami Beach, Florida. Problem 2 courtesy of Luke Stein. Used with permission. 3. (30 points) Consider the market for apple juice. In this market, the supply curve is given by Qs = 10P) -5PA and the demand curve is given by Qp = 100-15Py + 10Py, where J denotes apple juice, A denotes apples, and T denotes tea. (a) (7 points) Assume that PA is fixed at $1 and Py = 5. Calculate the equilibrium price and quantity in the apple juice market. (b) (7 points) Suppose that a poor harvest season raises the price of apples to PA = 2. Find the new equilibrium price and quantity of apple juice. Draw a graph to illustrate your answer. (c) (8 points) Suppose PA = 1 but the price of tea drops to Py = 3. Find the new equilibrium price and quantity of apple juice. (d) (8 points) Suppose PA = 1. Pr = 5, and there is a price ceiling on apple juice of Py = 5. What is the excess demand for apple juice as a result? Draw a graph to illustrate your answer. Problem 3 courtesy of William Wheaton. Used with permission. 4. (25 points) You have been asked to analyze the market for steel. From public sources, you are able to find that last year's price for steel was $20 per ton. At this price, 100 million tons were sold on the world market. From trade association data you are able to obtain estimates for the own price elasticities of demand and supply on the world markets as -0.25 for demand and 0.5 for supply. Assume that steel has linear demand and supply curves throughout. (a) (10 points) Solve for the equations of demand and supply in this market and sketch the demand and supply curves. (b) (15 points) Suppose that you discover that the current price of steel is $15 per ton and the current level of worldwide sales of steel is 150 million tons. The most recent elasticity estimates from the trade association this year are -0.125 for demand and 0.25 for supply. Describe the change in the supply and demand curves over the past year using your diagram from part (a). What sort of event(s) might explain the change