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.

The following data on x = score on a measure of test anxiety and y = exam score for a sample of n = 9 students are consistent with summary quantities given in the paper "Effects of Humor on Test Anxiety and Performance" (Psychological Reports 11999]: 1203-1212): Higher values for x indicate higher levels of anxiety. a. Construct a scatterplot, and comment on the features of the plot. b. Does there appear to be a linear relationship between the two variables? How would you characterize the relationship? c. Compute the value of the correlation coefficient. Is the value of r consistent with your answer to Part (b)? d. Is it reasonable to conclude that test anxiety caused poor exam performance? Explain.

$$\begin{matrix} \text{x} & \text{23} & \text{14} & \text{14} & \text{0} & \text{17} & \text{20} & \text{20} & \text{15} & \text{21}\\ \text{y} & \text{43} & \text{59} & \text{48} & \text{77} & \text{50} & \text{52} & \text{46} & \text{51} & \text{51}\\ \end{matrix}$$

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.

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.

In an effort to improve student performance, teachers at $12$ city schools are being asked to work a longer day next year for a relatively small increase in salary. For working an additional $190 \mathrm{~h}$, a teacher currently earning $\$ 79,400$ per year would see his or her salary increase to $\$ 83,500$ per year.

From the information given above, find the hourly rate the teachers will be paid for the extra hours they will work.

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 axial fan $2 \mathrm{~m}$ in diameter is used in a wind tunnel as shown (test section $1.2 \mathrm{~m}$ in diameter; test section velocity of $60 \mathrm{~m} / \mathrm{s}$ ). The rotational speed of the fan is $1800 \mathrm{rpm}$. Assume the density of the air is constant at $1.2 \mathrm{~kg} / \mathrm{m}^3$. There are negligible losses in the tunnel. The performance curve of the fan is identical to that shown in the mentioned figure. Compute the power needed to operate the fan.

Suppose that a soccer goalie has a save percentage of $85 \%$ this season. In a particular game, the opposing team takes 7 shots and she stops all 7 from going in the goal. The goalie is praised by her coach, but could her good performance be attributed to random chance? Describe how to simulate this situation using the methods of this chapter. Conduct at least 20 trials of your simulation and use the results to explain whether the praise was deserved.

The Red Lobster Restaurant chain conducts regular surveys of its customers to monitor the performance of individual restaurants. One of the questions asks customers to rate the overall quality of their last visit. The listed responses are Poor (1), Fair (2), Good (3), Very good (4), and Excellent (5). The survey also asks respondents whether their children accompanied them (1 5 yes and 2 5 no) to the restaurant. Graphically depict these data and describe your findings.

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.

Consider a Carnot-cycle heat pump with R22 as the working fluid; Heat is rejected from the R-22 at 100 F: during which process the R-22 changes from saturated vapor to saturated liquid. The heat is transferred to the R-22 at 30 F. a. Show the cycle on a T-diagram. b. Find the quality of the R-22 at the beginning and end of the isothermal heat addition process at 30 F. c. Determine the coefficient of performance for the cycle.

For the cycle of earlier problem, investigate the effects on cycle performance as the higher extraction pressure takes on other values. The operating conditions for the open feed. water heater are unchanged from those in earlier problem. Assume that condensate drains from the closed feedwater heater as saturated liquid at the higher extraction pressure. Also, feedwater leaves the heater at $12\ \mathrm{MPa}$ and a temperature equal to the saturation temperature at the extraction pressure. Construct suitable plots and discuss.

Air enters a frictionless, constant-area duct with $p_{1}$=135 kPa, $T_{1}$=500 K, and $V_{1}$=540 m/s. How much heat transfer is needed to choke the flow? Is the heat transfer into or out of the duct?