Doctors Hanson, Dominick, and Borchard are radiologists living in Fargo, North Dakota. They realize that many of the state's small, rural hospitals cannot afford to purchase their own magnetic resonance imaging devices (MRIs). Thus, the doctors are considering whether it would be feasible for them to form a corporation and invest in their own mobile MRI unit. The unit would be transported on a scheduled basis to more than 100 rural hospitals using an 18-wheel tractor-trailer. The cost of a tractor-trailer equipped with MRI equipment is approximately $\$ 1,250,000$. The estimated life of the investment is eight years, after which time its salvage value is expected to be no more than $\$ 100,000$. The doctors anticipate that the investment will generate incremental revenue of $\$ 800,000$ per year. Incremental expenses (which include depreciation, insurance, fuel, maintenance, their salaries, and income taxes) will average $\$ 700,000$ per year. Net incremental cash flows will be reinvested back into the corporation. The only difference between incremental cash flows and incremental income is attributable to depreciation expense. The doctors require a minimum return on their investment of 12 percent.

What nonfinancial factors should the doctors consider in making this decision?

From the trailer hitch from the figure has loads applied as shown in the figure. The tongue weight of $980 \mathrm{~N}$ acts downward and the pull force of $4905 \mathrm{~N}$ acts horizontally. Using the dimensions of the ball bracket in the figure, draw a free-body diagram of the ball bracket and find the tensile and shear loads applied to the two bolts that attach the bracket to the channel in the figure, determine the horizontal force that will result on the ball from an impact between the ball and the tongue of the $2000-\mathrm{kg}$ trailer if the hitch deflects $2.8 \mathrm{~mm}$ dynamically on impact. The tractor weighs $9807 \mathrm{~N}$. The velocity at impact is $0.3 \mathrm{m/sec}$. (also see the figures) determine the contact stresses in the ball and the ball cup (not shown). Assume that the ball is $2-\mathrm{in} \mathrm{~dia}$ and the ill-fitting ball cup that surrounds it has an internal spherical surface $10\%$ larger in diameter than the ball.

A tractor-trailer truck has a drag area $C_D A=8 \mathrm{~m}^2$ bare and $6.7 \mathrm{~m}^2$ with an aerodynamic deflector (Fig. $7.18 \mathrm{~b}$ ). Its rolling resistance is $50 \mathrm{~N}$ for each mile per hour of speed. Determine the total horsepower required at sea level with and without the deflector if the truck moves at (a) $55\ \mathrm{mi} / \mathrm{h}$ and (b) $75\ \mathrm{mi} / \mathrm{h}$.

Chipsealing is a common and relatively inexpensive way to pave a road. A layer of hot tar is sprayed onto the existing road surface and then stone chips are spread over the surface. A heavy roller then embeds the chips in the tar. Once the tar cools, most of the stones are trapped. However, some loose stones are scattered over the surface. They eventually will be swept up by a street cleaner, but if cars drive over the road before then, the rear tires on a leading car can launch stones backward toward a trailing car (Fig, 4.42). Assume that the stones are launched at speed $v_0=11.2 \mathrm{~m} / \mathrm{s}(25$ $\mathrm{mi} / \mathrm{h}$ ), matching the speed of the cars. Also assume that stones can leave the tires of the lead car at road level and at any angle and not be stopped by mud flaps or the underside of the car. In terms of car lengths $L_c=4.50 \mathrm{~m}$, what is the least separation $L$ between the cars such that stones will not hit the trailing car?

Suppose that you are driving an 18-wheeler tractor-trailer truck along the highway. A car pulls up alongside your truck and then moves ahead very slowly. As it passes, the combined sound of the car and truck engines pulsates louder and softer. The combined sound can be either a sum of the two sinusoids or a product of them.

At what rate is the car's engine rotating?

Doctors Mowtain, Lawrence, and Curley are radiologists living in Yukville, Maine. They realize that many of the state's small, rural hospitals cannot afford to purchase their own magnetic resonance imaging devices (MRIs). The doctors are considering whether it would be feasible for them to form a corporation and invest in their own MRI unit. The unit would be transported on a scheduled basis to more than 80 rural hospitals using an 18-wheel tractor-trailer. The cost of a tractor-trailer equipped with MRI equipment is approximately $\$ 1,500,000$. The estimated life of the investment is nine years, after which time its salvage value is expected to be no more than $\$ 200,000$.

The doctors anticipate that the investment will generate incremental revenue of $\$ 900,000$ per year. Incremental expenses (which include depreciation, insurance, fuel, maintenance, their salaries, and income taxes) will average $\$ 800,000$ per year. Net incremental cash flows will be reinvested back into the corporation. The only difference between incremental cash flows and incremental income is attributable to depreciation expense. The doctors require a minimum return on their investment of 15 percent.

Compute the net present value of the proposal using the tables in Exhibits 26-3 and 26-4. Comment on what the actual rate of return might be.

Fission tracks are trails found in uranium-bearing minerals, left by fragments released during fission events. The article “Yo-yo Tectonics of the Nigde Massif During Wrenching in Central Anatolia” reports that fifteen tracks on one rock specimen had an average track length of $13\mu m$ with a standard deviation of $2 \mu \mathrm{m}.$ Assuming this to be a random sample from an approximately normal population, find a 99% confidence interval for the mean track length for this rock specimen.

Snakes deposit chemical trails as they travel through their habitats. These trails are often detected and recognized by lizards, which are potential prey. The ability to recognize their predators via tongue flicks can often mean life or death for lizards. Scientists from the University of Antwerp were interested in quantifying the responses of juveniles of the common lizard (Lacerta vivipara) to natural predator cues to determine whether the behavior is learned or congenital. Seventeen juvenile common lizards were exposed to the chemical cues of the viper snake. Their responses, in number of tongue flicks per 20 minutes, are presented in the following table.

$$\begin{array}{llllll} \hline 425 & 510 & 629 & 236 & 654 & 200 \\ 276 & 501 & 811 & 332 & 424 & 674 \\ 676 & 694 & 710 & 662 & 633 & \\ \hline \end{array}$$

Find and interpret a 90% confidence interval for the mean number of tongue flicks per 20 minutes for all juvenile common lizards. Assume a population a standard deviation of} 90.0.

A typical tractor-trailer will move $18$ tons of air per mile at $55 \mathrm{~mph}$. Air resistance increases with speed, causing fuel efficiency to decrease at higher speeds. At highway speeds, a certain truck's fuel efficiency $t$, in miles per gallon ($\mathrm{mpg}$), can be approximated by

$$t=-0.1 s+13.1,$$

where $s$ is the speed of the truck, in miles per hour ($\mathrm{mph}$). Graph the equation and then use the graph to estimate the fuel efficiency at $66 \mathrm{~mph}$.

Doctors Hanson, Dominick, and Borchard are radiologists living in Fargo, North Dakota. They realize that many of the state's small, rural hospitals cannot afford to purchase their own magnetic resonance imaging devices (MRIs). Thus, the doctors are considering whether it would be feasible for them to form a corporation and invest in their own mobile MRI unit. The unit would be transported on a scheduled basis to more than 100 rural hospitals using an 18-wheel tractor-trailer. The cost of a tractor-trailer equipped with MRI equipment is approximately $\$ 1,250,000$. The estimated life of the investment is eight years, after which time its salvage value is expected to be no more than $\$ 100,000$. The doctors anticipate that the investment will generate incremental revenue of $\$ 800,000$ per year. Incremental expenses (which include depreciation, insurance, fuel, maintenance, their salaries, and income taxes) will average $\$ 700,000$ per year. Net incremental cash flows will be reinvested back into the corporation. The only difference between incremental cash flows and incremental income is attributable to depreciation expense. The doctors require a minimum return on their investment of 12 percent.

Compute the return on average investment of the proposal.

Here are three situations in which consumers might need some protection. A motorist asks for a tow rope 'strong enough for my trailer'. It breaks the first time he tries to use it. Do you think the consumer needs some legal protection in these cases? For each example. identify which part of UK consumer protection laws have broken by the business selling the goods.

Suppose you park your car at a trailhead in a national park and begin a 2-hr hike to a lake at 7 A.M. on a Friday morning. On Sunday morning, you leave the lake at 7 A.M. and start the 2-hr hike back to your car. Assume the lake is 3 mi from your car. Let f(t) be your distance from the car t hours after 7 A.M. on Friday morning and let g(t) be your distance from the car t hours after 7 A.M. on Sunday morning. Evaluate f(0), f(2), g(0), and g(2).

A random sample of 502 Vail Resorts' guests were asked to rate their satisfaction on various attributes of their visit on a scale of 1-5 with 1= very unsatisfied and 5= very satisfied. The regression model was Y= overall satisfaction score, $X_1$= lift line wait, $X_2$= amount of ski trail grooming, $X_3$= ski patrol visibility, and $X_4$= friendliness of guest services. (a) Calculate the t statistic for each coefficient to test for $\beta_j=0$. (b) Look up the critical value of Student's t in Appendix D for a two-tailed test at $\alpha=.01$. Which coefficients differ significantly from zero? (c) Use Excel to find a p-value for each coefficient.

$$\begin{array}{lcc} \hline \text { Predictor } & \text { Coefficient } & \text { SE } \\ \hline \text { Intercept } & 2.8931 & 0.3680 \\ \text { LiftWait } & 0.1542 & 0.0440 \\ \text { AmountGroomed } & 0.2495 & 0.0529 \\ \text { SkiPatroMisibility } & 0.0539 & 0.0443 \\ \text { FriendlinessHosts } & -0.1196 & 0.0623 \\ \hline \end{array}$$

The tractor-trailer unit is moving down the incline with a speed of 5 mi/hr when the driver brakes the tractor to a stop in a distance of 4 ft. Estimate the percent increase n in the hitch-force component which is parallel to the incline, compared with the force present at steady speed. The cart and its load combined weigh 500 lb. State any assumptions.