William Prout (1815) proposed that all other atoms are built up of hydrogen atoms, suggesting that all elements should have integral atomic masses based on an atomic mass of one for hydrogen. This hypothesis appeared discredited by the discovery of atomic masses, such as $24.3 \mathrm{u}$ for magnesium and $35.5 \mathrm{u}$ for chlorine. In terms of modern knowledge, explain why Prout's hypothesis is actually quite reasonable.

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.

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

Nearly all tall tale heroes and their counterparts in epics, myths, and legends display superhuman abilities. Modern forms of entertainment, such as comic books and action movies, also feature heroes with super-powers. In an essay, discuss how Pecos Bill's abilities are similar to or different from those of another heroic character with which you are familiar. Cite details from the tale to support your ideas.

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?

Insert a colon where necessary. If the sentence is correct, write C in the blank.
______The most popular sports in the United States are football, basketball, and baseball.

Modern jet engines have vanes that are deployed to produce a reverse thrust just after a plane touches down on a runway. The air flow rate through a particular engine is $100 \mathrm{~kg} / \mathrm{s}$, and the combustion gases exit the engine at a speed of $800 \mathrm{~m} / \mathrm{s}$ relative to the engine. The fuel-air ratio is 1 to 40 in this case. Calculate the reverse thrust produced by the vanes for the configuration shown.

{a) Summarize What was the Monroe Doctrine?

{b) Clarify Problems Would the United States have looked weak if it had jointly issued a warning with Britain? Explain.

The United States Postal Service delivers about

$$2 ^ { 8 } \cdot 5 ^ { 2 }$$

pieces of mail each second. There are

$$2 ^ { 8 } \cdot 3 ^ { 4 } \cdot 5 ^ { 2 }$$

seconds in 6 days. How many pieces of mail does the United States Postal Service deliver in 6 days? Write your answer as an expression involving powers.

(a) Recall: What connections does Rodriguez draw between Addison's London and modern-day Tijuana?
(b) Recall: As a journalist, in what way must Rodriguez present the border town of Tijuana?
(c) Speculate: Because of th e parallels Rodriguez notes between him self and Tijuana, do you think he can be objective in his presentation of the city? Why or why not?

Mary Wade owns a small business that rents parking spaces to students at the local university. Mary’s typical rental contract requires the student to pay the year’s rent of $720 ($60 per month) in advance. When Mary prepares financial statements at the end of December, her accountant requires that Mary spread the $720 over the 12 months that a parking space is rented. Therefore, Mary can recognize only$240 revenue (4 months) from each contract in the year the cash is collected and must defer recognition of the remaining $480 (8 months) to next year. Mary argues that getting students to agree to rent the parking space is the most difficult part of the activity so she ought to be able to recognize all$720 as revenue when the cash is received from a student.

Required:

Explain why generally accepted accounting principles require the use of accrual accounting rather than cash-basis accounting for transactions like the one described here.

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.

Avoid repetition by replacing the boldfaced word or expression with a synonym from the following words.

$$\begin{array}{lllll}\text { eradicate } & \text { understudy } & \text { ungag } & \text { update } & \text { upheaval } \\ \text { upkeep } & \text { upturn } & \text { withdraw } & \text { withdrawal } & \text { withstand }\end{array}$$

____d Our neighbors have modernized their kitchen. It now has a decidedly modern look.

Modern vacuum pumps make it easy to attain pressures of the order of $10^{-13}$ atm in the laboratory. Consider a volume of air and treat the air as an ideal gas. (a) At a pressure of $9.00 \times 10^{-14}$ atm and an ordinary temperature of 300.0 K, how many molecules are present in a volume of $1.00 \mathrm{cm}^{3}$? (b) How many molecules would be present at the same temperature but at 1.00 atm instead?