You are concerned about the effects of texting on driving performance. Design a study to test the response time of drivers while texting and while driving only. How many seconds does it take for a driver to respond when a leading car hits the brakes? a. Describe the explanatory and response variables in the study. b. What are the treatments? c. What should you consider when selecting participants? d. Your research partner wants to divide participants randomly into two groups: one to drive without distraction and one to text and drive simultaneously. Is this a good idea? Why or why not? e. Identify any lurking variables that could interfere with this study. f. How can blinding be used in this study?

A force platform is a tool used to analyze the performance of athletes by measuring the vertical force the athlete exerts on the ground as a function of time. Starting from rest, a 65.0-kg athlete jumps down onto the platform from a height of 0.600 m. While she is in contact with the platform during the time interval 0 < t < 0.800 s, the force she exerts on it is described by the function $F=9200 t-11500 t^{2}$ where F is in newtons and t is in seconds. (a) What impulse did the athlete receive from the platform? (b) With what speed did she reach the platform? (c) With what speed did she leave it? (d) To what height did she jump upon leaving the platform?

A vapor-compression refrigeration cycle with Refrigerant 134 as the working fluid operates with an evaporator temperature of $50^{\circ} \mathrm{F}$ and a condenser pressure of $180\ \mathrm{lbf}/ \mathrm{in}^2$ Refrigerant enters the condenser at $140^{\circ} \mathrm{F}$ and exits as sat urated liquid. The cycle has a refrigeration capacity of $5\ \text{tons}$. Determine (a) the refrigerant mass flow rate, in $\mathrm{lb} / \mathrm{min}$. (b) the compressor isentropic efficiency. (c) the compressor power, in horsepower. (d) the coefficient of performance. Plot each of the quantities calculated in parts (b) through (d) for compressor exit temperatures varying from $130^{\circ} \mathrm{F}$ to for compressor exit temperatures varying from $130^{\circ} \mathrm{F}$ to $140^{\circ} \mathrm{F}$.

Refer to The Sport Journal (Winter 2004) study on the effectiveness of a speed-training program for football players. The decreases in 40-yard sprint times (time after training minus time before training) for 38 players are saved in the SPRINT file. An athlete's sprint performance will be classified as "improved" if the "after" time is less than the "before" time, and classified as "Not Improved" if otherwise. a. Find an estimate for the true proportion of all high school athletes who attain improved sprint times after participating in the speed-training program. b. Convert the estimate, part a, into a 95% confidence interval. Give a practical interpretation of the result. c. How many high school athletes should be sampled to estimate the true proportion to within .03 with 95% confidence?

Assume the role of assistant buyer for a costume jewelry store. You are ordering a shipment of earrings in five styles from a supplier. The cost of the earrings is $\$ 1.50$ per pair. You know that if you set too low a selling price the earrings will not sell well. The buyer (judge) has asked you to prepare a pricing strategy for the earrings. Among the decisions you must make is whether to price all the styles at one price point or to price the different styles at separate price points.

Present your pricing strategy to your supervisor (judge).

You will be evaluated on how well you meet the following performance indicator:

Use psychological pricing to adjust base prices

Performance of stock screeners. Recall, from Exercise $6.36$ (p. 326), that stock screeners are automated tools used by investment companies to help clients select a portfolio of stocks to invest in. The data on the annualized percentage return on investment (as compared to the Standard & Poor's 500 Index) for 13 randomly selected stock screeners provided by the American Association of Individual Investors (AAII) are repeated in the accompanying table. You want to determine whether $\mu$, the average annualized return for all AAII stock screeners, is positive (which implies that the stock screeners perform better, on average, than the S&P 500). An XLSTAT printout of the analysis is shown on the top of page 394. Locate the observed significance level ( $p$-value) on the printout.

Performance data for a pump are

$$\begin{matrix} \text{H (ft)} & \text{90} & \text{87} & \text{81} & \text{70} & \text{59} & \text{43} & \text{22}\\ \text{Q (cfm)} & \text{0} & \text{50} & \text{100} & \text{150} & \text{200} & \text{250} & \text{300}\\ \end{matrix}$$

The pump is to be used to move water between two open reservoirs with an elevation increase of 24 ft. The connecting pipe system consists of 1750 ft of commercial steel pipe containing two $90^{\circ}$ elbows and an open gate valve. Find the flow rate if we use (a) 8-in., (b) 10-in., and (c) 12-in. (nominal) pipe.

A simple solar collector is built by placing a 5-cm-diameter clear plastic tube around a garden hose whose outer diameter is 1.6 cm. The hose is painted black to maximize solar absorption, and some plastic rings are used to keep the spacing between the hose and the clear plastic cover constant. During a clear day, the temperature of the hose is measured to be $65^\circ C,$ while the ambient air temperature is $26^\circ C.$ Determine the rate of heat loss from the water in the hose per meter of its length by natural convection. Also, discuss how the performance of this solar collector can be improved. Evaluate air properties at an average temperature of $50^\circ C$ and 1 atm pressure. Is this a good assumption?

Prof. Hardtack gave four Friday quizzes last semester in his senior tax accounting class. A random sample of 10 student scores is shown for each quiz.

(a) Find the sample mean, standard deviation, and coefficient of variation for each quiz.

(b) How do these data sets differ in terms of center and variability?

(c) Briefly describe and compare student performance on each quiz.

Quiz 1: 60, 60, 60, 60, 71, 73, 74, 75, 88, 99

Quiz 2: 65, 65, 65, 65, 70, 74, 79, 79, 79, 79

Quiz 3: 66, 67, 70, 71, 72, 72, 74, 74, 95, 99

Quiz 4: 10, 49, 70, 80, 85, 88, 90, 93, 97, 98

In order to study the relationship between the amount of sleep a student gets and his or her school performance, a researcher collected data from 120 students. The two-way frequency table shows the number of students who passed and failed an exam and the number of students who got more or less than 6 hours of sleep the night before.

To the nearest percent, find the probability that a student who got less than 6 hours of sleep failed the exam.

We could improve the performance of the waterproofing process discussed in the previous exercise by making an adjustment that moves the center of the process to $\mu=2500 \mathrm{~mm}$, the center of the specifications. We should do this even if the original specifications remain in force, because this will require less sealer and therefore cost less. Suppose that we succeed in moving $\mu$ to 2500 with no change in the process variability $\sigma$, estimated by $s=383.8$. (a) What are $\mathrm{C}^{\wedge} \mathrm{p}$ and $\mathrm{C}^{\wedge} \mathrm{pk}$ with the original specifications? Compare the values with those from part (a) of the previous exercise. (b) What are $\mathrm{C}^{\wedge} \mathrm{p}$ and $\mathrm{C}^{\wedge} \mathrm{pk}$ with the tightened specifications? Again compare with the previous results.

The following list gives a number of measures associated with the Balanced Scorecard:

a. Number of new customers
b. Percentage of customer complaints resolved with one contact
c. Unit product cost
d. Cost per distribution channel
e. Suggestions per employee
f. Warranty repair costs
g. Consumer satisfaction (from surveys)
h. Cycle time for solving a customer problem
i. Strategic job coverage ratio
j. On-time delivery percentage
k. Percentage of revenues from new products

1. Classify each performance measure as belonging to one of the following perspectives: financial, customer, internal business process, or learning and growth.

2. Suggest an additional measure for each of the four perspectives.

Oil executives frequently compare the performance and efficiency of their company with those of other major oil companies. The following data is taken from Total Oil's $2013$ accounts.

$$\begin{array}{|l|l|l|l|l|l|l|l|} \hline\text{ Credit } & \text{ Creditors } & \text{ Debtors } & \text{ Long-term } & \text{ Inventories } & \text{ Cost of } & \text{ Capital } & \text{ Credit }\\ \text{ sales (\$m)} & \text{ (accounts } & \text{ (accounts } & \text{ loans(\$m)} & \text{ (\$m) } & \text{ sales (\$m) } & \text{ employed } & \text{ purchases } \\ & \text{ payable) } & \text{ receivable) } &&&& \text{ (\$m) } & \text{ (author’s } \\ & \text{ (\$m) } & \text{ (\$m) } &&&&& \text{ estimate)(\$m)} \\ \hline227969 & 30282 & 23422 & 34574 & 22097 & 160849 & 177555 & 160000 \\ \hline \end{array}$$

Calculate the creditor days ratio for Total Oil in $2013$.

Is the number of years of competitive running experience related to a runner's distance running performance? The data on nine runners, obtained from the study by Scott Powers and colleagues, are shown in the table:

Runner: 1, 2, 3, 4, 5, 6, 7, 8, 9 Years of Competitive Running: 9, 13, 5, 7, 12, 6, 4, 5, 3 10-Kilometer Finish Time (minutes): 33.15, 33.33, 33.50, 33.55, 33.73, 33.86, 33.90, 34.15, 34.90

a. Calculate the rank correlation coefficient between years of competitive running x and a runner's finish time in the 10-kilometer race. b. Do the data provide evidence to indicate a significant rank correlation between y and x? Test using $\alpha$=.05.