According to the Federal Bureau of Investigation, there is a violent crime in the United States every 22 seconds ( $A B C$ News, September 25, 2007). Assume that the time between successive violent crimes is exponentially distributed.

a. What is the probability that there is a violent crime in the United States in the next one minute?

b. If there has not been a violent crime in the previous minute, what is the probability that there will be a violent crime in the subsequent minute?

Are the marks one receives in a course related to the amount of time spent studying the subject? To investigate this mysterious possibility, a student took a random sample of 10 students who had enrolled in an accounting class last semester. He asked each to report his or her mark in the course and the total number of hours spent studying accounting. These data are listed here: Study

$$\begin{array}{rllllllllll}\text { time } & 40 & 42 & 37 & 47 & 25 & 44 & 41 & 48 & 35 & 28 \\ \text { Marks } & 77 & 63 & 79 & 86 & 51 & 78 & 83 & 90 & 65 & 47\end{array}$$

Calculate the covariance.

In many of the world’s poorest countries, nearly 50 percent of the population is under 15 years of age. If these people are to help improve the productivity of their economies, they must be trained in modern methods of production. In 2000, just over 4 million of the 8.8 million people of Chad were under 15. Explain why it would be difficult for many of these children to be educated and become productive members of a growing economy.

Listed below are nine technical accounting terms used in this chapter:

$$\begin{array}{lll}\text { Unrecorded revenue } & \text { Adjusting entries } & \text { Accrued expenses } \\ \text { Book value } & \text { Matching principle } & \text { Accumulated depreciation } \\ \text { Unearned revenue } & \text { Materiality } & \text { Prepaid expenses }\end{array}$$

Each of the following statements may (or may not) describe one of these technical terms. For each statement, indicate the accounting term described, or answer "None" if the statement does not correctly describe any of the terms.
h. An expense representing the systematic allocation of an asset's cost over its useful life.

What equipment would you need to design an experiment that measures relative humidity?

In the catalytic converters fitted to modern cars, carbon monoxide and oxides of nitrogen in the exhaust gas are converted to other substances.

a. i. Why is carbon monoxide removed?

ii. Give one harmful effect of nitrogen dioxide.

b. What is meant by a catalytic reaction?

c. In one reaction in a catalytic converter, nitrogen monoxide (NO) reacts with carbon monoxide to form nitrogen and carbon dioxide. Write a balanced equation for this reaction.

The first bridge over the Piscataqua River, built in $1794$, was the longest bridge in the world. The modern bridge, completed in $1971$, is not the world's longest, but it is well known for its elegant symmetric design. The bridge connects Kittery, Maine with Portsmouth, New Hampshire.

Does the Piscataqua River Bridge have any lines of symmetry? If so, make a simple sketch of the bridge and draw all of its lines of symmetry.

A design change is required in the valve interface circuit of the temperature-control system shown . The new design will have a valve interface input resistance of $10 \mathrm{k} \Omega$. Determine the effect this change has on the temperature-to-voltage conversion circuit.

The following are nine technical accounting terms introduced or emphasized in this chapter:

$$\begin{array}{lll}\text { Responsibility margin } & \text { Transfer price } & \text { Common fixed costs } \\ \text { Contribution margin } & \text { Cost-plus transfer price } & \text { Traceable fixed costs } \\ \text { Performance margin } & \text { Product costs } & \text { Committed fixed costs }\end{array}$$

Each of the following statements may (or may not) describe one of these technical terms. For each statement, indicate the accounting term described, or answer "None" if the statement does not correctly describe any of the terms.

b. Cost to produce plus a predetermined markup.

Solve the given problems.

In a modern hotel, where the elevators are directly observable from the lobby area (and a person can see from the elevators), a person in the lobby observes one of the elevators rising at the rate of $12.0$ ft/s. If the person was $50.0$ ft from the elevator when it left the lobby, how fast is the angle of elevation of the line of sight to the elevator increasing $10.0$ s later?

Use context clues and your knowledge of specialized vocabularies to answer the following question. Compared with black schools under apartheid, American schools are SHANGRI-LAS, with modern textbooks, school buses, computers, libraries, lunch programs and dedicated teachers. What is the most likely meaning of Shangri-Las in the essay? A flawed institutions B average schools C ideal places D suitable locales

Listed below are nine technical accounting terms:

$$\begin{array}{lll}\text { Variable costs } & \text { Relevant range } & \text { Contribution margin } \\ \text { Break-even point } & \text { Fixed costs } & \text { Semivariable costs } \\ \text { Economies of scale } & \text { Sales mix } & \text { Unit contribution margin }\end{array}$$

Each of the following statements may (or may not) describe one of these technical terms. For each statement, indicate the accounting term described, or answer "None" if the statement does not correctly describe any of the terms.

e. Unit sales price minus variable cost per unit.

What is visual hierarchy in map design? How is the hierarchy related to the map purpose?

The United States has a land area of about

$$3,536,278\ mi^2.$$

Illinois has a land area of about

$$57,918\ mi^2.$$

What is the probability that a location in the United States chosen at random is not in Illinois? Give your answer to the nearest tenth of a percent. How can you solve this problem using the complement of an event? How do you write a fraction as a percent?