A job-performance evaluation form has these categories: 1=excellent; 2=good; 3=satisfactory; 4=poor; 5=unacceptable. Based on 15 client reviews, one employee had median rating of 4; mode rating of 1. The employee was pleased that most clients had rated her as excellent. The supervisor said improvement was needed because at least half the clients had rated the employee at the poor or unacceptable level. Comment on the different perspectives.

The following experiment compares the performance of linear probing and quadratic probing. You will need a list of 500 names or user names that can be obtained from your instructor or from a system administrator. Implement a hash table of size 1000. Count the number of collisions that occur for both linear probing and quadratic probing when 500 names are added to the table. Repeat the experiment for tables of size 950, 900, 850, 800, 750, 700, 650, and 600.

(a) Give two original examples of time series data.

(b) Give two original examples of crosssectional data. In each case, identify the unit of observation carefully. If the data are both crosssectional and time series, explain why. Hint: Do not restrict yourself to published data, and consider data describing your own life (e.g., sports performance or financial data). You need not list any data, merely describe them and perhaps show a few typical data values.

Solder-joint inspections. Refer to Exercise $7.44$ (p. 387), in which the performance of a particular type of laser-based inspection equipment was investigated. Assume that the standard deviation of the number of solder joints inspected on each run is $1.2$. If $\alpha=.05$ is used in conducting the hypothesis test of interest using a sample of 48 circuit boards, and if the true mean number of solder joints that can be inspected is really equal to $9.5$, what is the probability that the test will result in a Type II error?

Data giving the number of hours a person studied compared to his or her performance on an exam are given in the table:

$$\begin{array}{c|c} \text{Hours Studied} & \text{Exam Score} \\ x & y\\ \hline 0 & 50\\ 2 & 74\\ 4 & 85\\ 6 & 90\\ 8 & 92 \end{array}$$

(a) Find a least squares line of best fit to the above data. (b) What prediction would this line make for a student who studied 9 hours?

A freezer has a coefficient of performance of 2.40. The freezer is to convert 1.80 kg of water at $25.0^{\circ} \mathrm{C}$ to 1.80 kg of ice at $-5.0^{\circ} C$ in one hour. (a) What amount of heat must be removed from the water at $25.0^{\circ} C$ to convert it to ice at $-5.0^{\circ} C$? (b) How much electrical energy is consumed by the freezer during this hour? (c) How much wasted heat is delivered to the room in which the freezer sits?

The wattage of a commercial ice maker is 225 W and is the rate at which it does work. The ice maker operates just like a refrigerator or an air conditioner and has a coefficient of performance of 3.60. The water going into the unit has a temperature of $15.0^{\circ} \mathrm{C}$, and the ice maker produces ice cubes at $0.0^{\circ} \mathrm{C}$. Ignoring the work needed to keep stored ice from melting, find the maximum amount (in kg) of ice that the unit can produce in one day of continuous operation.

Flynn Industries has outsourced the delivery of its products and now wants to develop a tool to help evaluate its transportation carriers. The table at the bottom of the page shows the rating values associated with different levels of price, quality, and delivery performance, as well as criteria weights that reflect the relative importance of these dimensions. To illustrate how the ratings work, suppose a carrier has a damage level of 0.82%. This would fall between 0.75% and 1.0%, thereby garnering a rating of 2. The second table shows actual average performance levels for three carriers.

a. Use the weighted-point evaluation system to calculate the weighted average performance for each carrier. Which carrier is best under this system?

b. How would the results change if the weights for price, quality, and delivery shifted to 0.6, 0.2, and 0.2, respectively?

c. Based on the results, should Flynn Industries single source or not? What might stop Flynn from single sourcing?

True or false: (a) Work can never be converted completely into heat. (b) Heat can never be converted completely into work. (c) All heat engines have the same efficiency. (d) It is impossible to transfer a given quantity of heat from a cold reservoir to a hot reservoir. (e) The coefficient of performance of a refrigerator cannot be greater than 1. (j) All Carnot engines are reversible. (g) The entropy of a system can never decrease. (h) The entropy of the universe can never decrease.

A Carnot vapor refrigeration cycle employs Refrigerant $134 a$ as the working fluid. The refrigerant enters the condenser as saturated vapor at $28^{\circ} \mathrm{C}$ and leaves it as a saturated liquid. The evaporator operates at a temperature of $-10^{\circ} \mathrm{C}$. Find, in $\mathrm{kJ}$ per $\mathrm{kg}$ of refrigerant flow,

(a) the work input to the compressor.

(b) the work developed by the turbine.

(c) the heat transfer to the refrigerant passing via the evaporator. What is the coefficient of performance of the cycle?

Consider the piping system of the figure, with all the dimensions, parameters, minor loss coefficients, etc., of the earlier problem. The pump's performance follows a parabolic curve fit, $H_{\text {wailate }}=H_0-a \dot{V}^2$, where $H_0=19.8 \mathrm{~m}$ is the pump's shutoff head, and $a=0.00426 \mathrm{~m} /(\mathrm{Lpm})^2$ is a coefficient of the curve fit. Find the operating volume flow rate $\dot{V}$ in Lpm (liters per minute), and compare it with that of the earlier problem. Discuss.

Refrigerant 134a is the working fluid in a vaporcompression heat pump that provides 35 kW to heat a dwelling on a day when the outside temperature is below freezing. Saturated vapor enters the compressor at 1.6 bar, and saturated liquid exits the condenser, which operates at 8 bar. Determine for isentropic compression a. the refrigerant mass flow rate, in kg/s. b. the compressor power, in kW. c. the coefficient of performance. Recalculate the quantities in parts (b) and (c) for an isentropic compressor efficiency of 75%.

Match the plot with the description of the sample.

$$\begin{array}{l|l} 6 & 78 \\ 7 & 455888 \\ 8 & 1355889 \\ 9 & 00024 \end{array}$$

Key: $6 \mid 7=67$

a) Time (in minutes) it takes a sample of employees to drive to work

b) Grade point averages of a sample of students with finance majors

c) Top speeds (in miles per hour) of a sample of high-performance sports cars

d) Ages (in years) of a sample of residents of a retirement home

Of the 281 players with at least 300 plate appearances in the 2008 Major League Baseball season, Jeff Mathis of the Los Angeles Angels had the lowest batting average ( $0.194)$ and Brad Wilkerson of the Toronto Blue Jays scored the fewest runs (21). Overall, the mean batting average was $0.272$, with a standard deviation of $0.027$, and the mean number of runs scored was $65.0$, with a standard deviation of 23.6. Which PERFORMANCE was worse? Explain, using the methods of this chapter.