Problem 8.045 SI

Consider a regenerative vapor power cycle with two feedwater heaters, a closed one and an open one, and reheat. Steam enters the first turbine stage at 12 MPa, 560°C, and expands to 2 MPa. Some steam is extracted at 2 MPa and fed to the closed feedwater heater. The remainder is reheated at 2 MPa to 520°C and then expands through the second-stage turbine to 0.3 MPa, where an additional amount is extracted and fed into the open feedwater heater operating at 0.3 MPa.

The steam expanding through the third-stage turbine exits at the condenser pressure of 60 kPa. Feedwater leaves the closed heater at 210°C, 12 MPa, and condensate exiting as saturated liquid at 2 MPa is trapped into the open feedwater heater. Saturated liquid at 0.3 MPa leaves the open feedwater heater. Assume all pumps and turbine stages operate isentropically.


Determine for the cycle:

(a) the heat transfer to the working fluid passing through the steam generator, in kJ per kg of steam entering the firststage turbine.

(b) the percent thermal efficiency.

(c) the heat transfer from the working fluid passing through the condenser to the cooling water, in kJ per kg of steam entering the first-stage turbine.

Kate recently invested in real estate with the intention of selling the property one year from today. She has modeled the returns on that investment based on three economic scenarios. She believes that if the economy stays healthy, then her investment will generate a 30 percent return. However, if the economy softens, as predicted, the return will be 10 percent, while the return will be -25 percent if the economy slips into a recession.

1) If the probabilities of the healthy, soft, and recessionary states are 0.6 , 0.3 , and 0.1 , respectively, then calculate the coefficient of variation for the investment?

2) Barbara is considering investing in a stock and is aware that the return on that investment is particularly sensitive to how the economy is performing. Her analysis suggests that four states of the economy can affect the return on the investment. Using the table of returns and probabilities below calculate the coefficient of variation for the investment?

3) Ben would like to invest in gold and is aware that the returns on such an investment can be quite volatile. Use the following table of states, probabilities, and returns and calculate the coefficient of variation for the investment?

Consider a regenerative vapor power cycle with two feedwater heaters, a closed one and an open one, and reheat. Steam enters the first turbine stage at 12 MPa, 560 °C, and expands to 1.5 MPa. Some steam is extracted at 1.5 MPa and fed to the closed feedwater heater. The remainder is reheated at 1.5 MPa to 440 °C and then expands through the second-stage turbine to 0.3 MPa, where an additional amount is extracted and fed into the open feedwater heater operating at 0.3 MPa. The steam expanding through the third-stage turbine exits at the condenser pressure of 10 kPa. Feedwater leaves the closed heater at 220 °C, 10 MPa, and condensate exiting as saturated liquid at 1.5 MPa is trapped into the open feedwater heater. Saturated liquid at 0.3 MPa leaves the open feedwater heater. Assume all pumps and turbine stages operate isentropically. Determine for the cycle:
      a) The rate of heat transfer to the working fluid passing through the steam generator, in kJ per kg of steam entering the first-stage turbine.
      b) The thermal efficiency.
      c) The rate of heat transfer from the working fluid passing through the condenser to the cooling water, in kJ per kg of steam entering the first-stage turbine.

1) The number of cracks in a section of interstate highway that are significant enough to require repair is assumed to follow a Poisson distribution with mean of three cracks every five miles. What is the probability that there are exactly two cracks that require repair in 3 miles of highway?

2) The volume of a shampoo filled into a container is a continuous random variable uniformly distributed with 240 and 260 milliliters. What is the probability that the container is filled with MORE THAN the advertised target of 255 milliliters?

3) The time between arrivals of taxis at a busy intersection is exponentially distributed with a mean of 10 minutes. What is the probability that you wait between 10 and 20 minutes for a taxi?

1). A group of students plans a tour. The charge per student is $66 if 25 students go on a trip. If more that 25 students participated, the charge per student is reduced by $2 times the number of students over 25. Find the number of students that will furnish the maximum revenue. The number of students that will furnish the maximum revenue is ______? The maximum revenue is $_______?

2) A motorboat is capable of traveling at a speed of 15 miles per hour in still water. On a particular​ day, it took 30 minutes longer to travel a distance of 18 miles upstream than it took to travel the same distance downstream. What was the rate of current in the stream on that​ day?

Larry offered to sell Stanley his car and told Stanley that the car had been driven only 25,000 miles and had never been in an accident. Stanley hired Cohen, a mechanic, to appraise the condition of the car, and Cohen said that the car probably had at least 50,000 miles on it and probably had been in an accident. In spite of this information, Stanley still thought the car would be a good buy for the price, so he purchased it. Later, when the car developed numerous mechanical problems, Stanley sought to rescind the contract on the basis of Larry's fraudulent misrepresentation of the auto's condition. Will Stanley be able to rescind his contract? Discuss.

The maintenance manager at a trucking company wants to build a regression model to forecast the time (in years) until the first engine overhaul based on four explanatory variables: (1) annual miles driven (in 1,000s of miles), (2) average load weight (in tons), (3) average driving speed (in mph), and (4) oil change interval (in 1,000s of miles). Based on driver logs and onboard computers, data have been obtained for a sample of 25 trucks. A portion of the data is shown in the accompanying table.

a. For each explanatory variable, discuss whether it is likely to have a positive or negative causal effect on time until the first engine overhaul.

b. Estimate the regression model. (Negative values should be indicated by a minus sign. Round your answers to 4 decimal places.)

c. Based on part (a), are the signs of the regression coefficients logical?

d. What is the predicted time before the first engine overhaul for a particular truck driven 56,000 miles per year with an average load of 21 tons, an average driving speed of 59 mph, and 22,000 miles between oil changes. (Round coefficient estimates to at least 4 decimal places and final answer to 2 decimal places.)

1.         Corey is the city sales manager for “RIBS,” a national fast food franchise. Every working day, Corey drives his car as follows:

                                                Miles

Home to office                           20

Office to RIBS No. 1                 15

RIBS No. 1 to No. 2                    8

RIBS No. 2 to No. 3                    3

RIBS No. 3 to office                  10

Office to home                           20

Corey’s deductible daily mileage is:

a.         0 miles.

b.         36 miles.

c.         46 miles.

d.         56 miles.

e.         76 miles.

2.         Which of the following trips, if any, will qualify for the travel expense deduction?

a.         Dr. Jones, a general dentist, attends a two-day seminar on financial planning.

b.         Dr. Brown, an undergraduate pre-med student, attends a two-day seminar on developing a medical practice.

c.         Paul, a romance language high school teacher, spends summer break in France, Portugal, and Spain improving his language skills.

d.         Myrna went on a two-week vacation in Boston. While there, she visited her employer’s home office to have lunch with former co-workers.

e.         Mary, a CPA, attends a three-day seminar on state income taxation.

3.         Tax advantages of being self-employed (rather than being an employee) include:

a.         The self-employment tax is always lower than the Social Security tax.

b.         The overall limitation (50%) on meals does not apply.

c.         An office in the home deduction from AGI is available without having to meet the “convenience of the employer” test.

d.         Job-related expenses are deductions for AGI.

e.         Both (c) and (d) are advantages.

4.         When using the automatic mileage method, which of the following expenses, if any, also can be claimed?

a. Engine tune-up.

b. Parking.

c. Interest on automobile loan.

d. MACRS depreciation.

e. None of these.

5.         Which, if any, of the following is subject to a 50% cutback adjustment for the cost of meals in 2019?

a.         An airline pilot for an executive jet rental company who pays his own travel expenses while away from home on flights she pilots.

b.         Meals provided at cost to employees by a cafeteria funded by the employer/taxpayer.

c.         A Fourth of July company picnic for employees of the employer/taxpayer.

d.         A vacation trip to Bermuda awarded to the employer/taxpayer’s top salesperson, where the cost (including meals) is treated as a taxable bonus to the employee.

e.         None of these is subject to the 50% cutback.