An office building requires a heat transfer rate of $20\ \mathrm{kW}$ to maintain the inside temperature at $21^{\circ} \mathrm{C}$ when the outside temperature is $0^{\circ} \mathrm{C}$. A vapor-compression heat pump with Refrigerant $22\mathrm{a}$ as the working fluid is to be used to provide the necessary heating. The compressor operates adiabatically with an isentropic efficiency of $82 \%$. Specify appropriate evaporator and condenser pressures of a cycle for this purpose assuming $\Delta T_{\text {cond }}=\Delta T_{\text {cvap }}=10^{\circ} \mathrm{C}$, as shown in figure. The states are numbered as in figure. The refrigerant exits the evaporator as saturated vapor and exits the condenser as saturated liquid at the respective pressures. Determine the (a) mass flow rate of refrigerant, in $\mathrm{kg} / \mathrm{s}$. (b) compressor power, in $\mathrm{kW}$. (c) coefficient of performance and compare with the coefficient of performance for a Carnot heat pump cycle operating between reservoirs at the inside and outside temperatures, respectively.. Compare the results with those of previous problem and discuss.

Explain why the following technique for transaction execution may provide better performance than just using strict two-phase locking: First execute the transaction without acquiring any locks and without performing any writes to the database as in the validation-based techniques, but unlike the validation techniques do not perform either validation or writes on the database. Instead, rerun the transaction using strict two-phase locking. (Hint: Consider waits for disk I/O.)

A windows air conditioner that consumes of 1 kW of electricity when running and has a coefficient of performance of 3 is placed in the middle of a room and is plugged in. The rate of cooling or heating this air conditioner will provide to the air in the room when running is (a) 3 kJ/s, cooling (b) 1 kJ/s, cooling (c) 0.33 kJ/s, heating (d) 1 kJ/s, heating (e) 3 kJ/s, heating

The following selected accounts appear in Shaw Company's unadjusted trial balance at December 31, 2018, the end of its fiscal year (all accounts have normal balances).

$$\begin{array}{lrlr} \text{ Prepaid advertising }& \$ 1,200 &\text{ Performance obligations }& \$ 5,400 \\ \text{ Wages expense }& 43,800 &\text{ Service fees revenue }& 87,000 \\ \text{ Prepaid insurance }& 3,420 &\text{ Rental income }& 4,900 \\ \end{array}$$

Prepare its adjusting entries at December 3 I. 2018. (1) using the financial statement effects template. and (2) in journal entry form using the following additional information.

1. Prepaid advertising at December 31 is $800.
2. Unpaid and unrecorded wages earned by employees in December are$1,300.
3. Prepaid insurance at December 31 is $2,280.
4. Perfomance obligations represent service fees collected in advance of when the services are provided to customers. Performance obligations at December 31 are$3,000.
5. Rent revenue of$ 1,000 owed by a tenant is not recorded at December 31 .

An engineer living at an elevation of $2500 \mathrm{ft}$ is conducting experiments to verify predictions of glider performance. To process data, the density of ambient air is needed. The engineer measures temperature $\left(74.3^{\circ} \mathrm{F}\right)$ and atmospheric pressure $(27.3$ inches of mercury). Compute density in units of $\mathrm{kg} / \mathrm{m}^3$. Compare the calculated value with data from the mentioned table and make a recommendation about the effects of elevation on density; that is, are the effects of elevation significant?

A one-sided confidence interval for p can be expressed as $p<\hat{p}+E \text { or } p>\hat{p}-E$, where the margin of error E is modified by replacing $z_{\alpha / 2}$ with $z_{\alpha}$. If Air America wants to report an on-time performance of at least x percent with 95% confidence, construct the appropriate one-sided confidence interval and then find the percent in question. Assume that a simple random sample of 750 flights results in 630 that are on time.

In the 2008 baseball season, first baseman Ryan Howard of the Philadelphia Phillies led the Major Leagues with 48 home runs (HR) and 146 runs batted in (RBI). Overall, using all players with at least 300 plate appearances, the mean number of HR was $14.9$ with a standard deviation of $9.8$, whereas the mean number of RBI was $62.5$ with a standard deviation of $25.5$. Which was the more impressive PERFORMANCE? Explain, using the methods of this chapter.

As shown in figure, an air conditioner operating at steady state maintains a dwelling at $70^{\circ} \mathrm{F}$ on a day when the outside temperature is $90^{\circ} \mathrm{F}$. If the rate of heat transfer into the dwelling through the walls and roof is $30,000\ \mathrm{Btu} / \mathrm{h}$, might a net power input to the air conditioner compressor of 3 hp be sufficient? If yes, determine the coefficient of performance. If no, determine the minimum theoretical power input, in hp.

Refrigerant 134 a enters the compressor of a vapor compression heat pump at $30 \mathrm{lbf} /$ in. $^2, 20^{\circ} \mathrm{F}$ and is compressed adiabatically to $200\ \mathrm{lbf} / \mathrm{in}^2, 160^{\circ} \mathrm{F}$. Liquid enters the expansion valve at $200\ \mathrm{lbf} / \mathrm{in}^2, 120^{\circ} \mathrm{F}$. At the valve exit, the pressure is $30 \mathrm{lbf/in.}^2$ Find

(a) the isentropic compressor efficiency.

(b) the coefficient of performance.

The adjusted trial balance of Estella Real Estate Appraisal at June 30, 2016, follows:

$$\begin{array}{c} \textbf{ESTELLA REAL ESTATE APPRAISAL}\\ \text{Adjusted Trial Balance}\\ \text{June 30, 2016}\\ \end{array}$$

$$\begin{array}{lrr} &\textbf{Balance}\\ \textbf{Account Title}&\textbf{Debit}&\textbf{Credit}\\ \text{Cash}&\$4,600\\ \text{Accounts Receivable}&5,300\\ \text{Office Supplies}&1,500\\ \text{Prepaid Insurance}&1,600\\ \text{Building}&77,000\\ \text{Accumulated Depreciation - Building}&&\$26,000\\ \text{Land}&13,500\\ \text{Accounts Payable}&&19,300\\ \text{Interest Payable}&&8,400\\ \text{Salaries Payable}&&1,900\\ \text{Unearned Revenue}&&5,300\\ \text{Notes Payable (long-term)}&&37,000\\ \text{Common Stock}&&3,000\\ \text{Retained Earnings}&&37,000\\ \text{Dividends}&27,200\\ \text{Service Revenue}&&48,900\\ \text{Insurance Expense}&4,300\\ \text{Salaries Expense}&33,000\\ \text{Supplies Expense}&200\\ \text{Interest Expense}&8,400\\ \text{Utilities Expense}&2,500\\ \text{Depreciation Expense - Building}&7,700\\ \text{Total}&\underline{\underline{\$186,800}}&\underline{\underline{\$186,800}}\\ \end{array}$$

Requirements

1. Prepare the company's income statement for the year ended June 30, 2016.
2. Prepare the company's statement of retained earnings for the year ended June 30, 2016.
3. Prepare the company's classified balance sheet in report form at June 30, 2016.
4. Journalize the closing entries.
5. Open the T-accounts using the balances from the adjusted trial balance, and post the closing entries to the T-accounts.
6. Prepare the company's post-closing trial balance at June 30, 2016.

The following performance scores have been recorded for 25 job applicants who have taken a preemployment aptitude test administered by the company to which they applied:

$$\begin{array}{rrrrrrrrr}66.6 & 75.4 & 66.7 & 59.2 & 78.5 & 80.8 & 79.9 & 87.0 & 94.1 \\ 70.2 & 92.8 & 86.9 & 92.8 & 66.8 & 65.3 & 100.8 & 76.2 & 87.8 \\ 71.0 & 92.9 & 97.3 & 82.5 & 78.5 & 72.0 & 76.2 & & \end{array}$$

Construct a frequency distribution and a histogram for these data.

Katie and Kim are attending a theater performance. Katie's seat is at floor level. She looks down at an angle of 18$^{\circ}$ to see the orchestra pit. Kim's seat is in the balcony directly above Katie. Kim looks down at an angle of 42$^{\circ}$ to see the pit. The horizontal distance from Katie's seat to the pit is 46ft. What is the vertical distance between Katie's seat and Kim's seat? Round to the nearest inch.

Performance data for a centrifugal fan of 3-ft diameter, tested at 750 rpm, are

$$\begin{matrix} \text{Volume flow rate Q (}{\mathrm{ft}^{3} /s)} & \text{106} & \text{141} & \text{176} & \text{211} & \text{246} & \text{282}\\ \text{Static pressure rise, }{\Delta p} (psi) & \text{0.075} & \text{0.073} & \text{0.064} & \text{0.050} & \text{0.033} & \text{0.016}\\ \text{Power output }{\mathscr{P} (hp)} & \text{2.75} & \text{3.18} & \text{3.50} & \text{3.51} & \text{3.50} & \text{3.22}\\ \end{matrix}$$

Plot the performance data versus volume flow rate. Calculate static efficiency, and show the curve on the plot. Find the best efficiency point, and specify the fan rating at this point. Using the fan, determine the minimum size square sheet-metal duct that will carry a flow of 200 $\mathrm{ft}^{3}$/s over a distance of 50 ft. Estimate the increase in delivery if the fan speed is increased to 1000 rpm.

A refrigerator uses refrigerant-134a as the working fluid and operates on an ideal vapor-compression refrigeration cycle between $0.12$ and for a condenser pressure of $0.9 \mathrm{MPa}$. The mass flow rate of the refrigerant is $0.05 \mathrm{~kg} / \mathrm{s}$. Show the cycle on a $T$-$s$ diagram with respect to saturation lines. Find $(a)$ the rate of heat removal from the refrigerated space and the power input to the compressor, $(b)$ the rate of heat rejection to the environment, and $(c)$ the coefficient of performance.