Numerade

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Leon Druch

Numerade educator

According to a recent report, the average American consumes 22.7 teaspoons of sugar each day (National Geographic Magazine, August 2013 ). Assuming that the distribution is approximately normal with a standard deviation of $\sigma=4.5,$ find each of the following values. a. What proportion of people consume more than 30 teaspoons of sugar a day? b. What proportion of people consume at least 20 teaspoons of sugar a day?

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Umar Sohail Qureshi

Numerade educator

Suppose that a committee is studying whether or not there is waste of time in our judicial system. It is interested in the mean amount of time individuals waste at the courthouse waiting to be called for jury duty. The committee randomly surveyed 81 people who recently served as jurors. The sample mean wait time was eight hours with a sample standard deviation of four hours. a. i. $\overline{x}=$ _____ ii. $s_{x}=$ _____ iii. $n=$ _____ iv. $n-1=$ _____ b. Define the random variables $X$ and $\overline{X}$ in words. c. Which distribution should you use for this problem? Explain your choice. d. Construct a 95$\%$ confidence interval for the population mean time wasted. i. State the confidence interval. ii. Sketch the graph. iii. Calculate the error bound. e. Explain in a complete sentence what the confidence interval means.

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Paul Gabriel

Numerade educator

Tour de France While cycling at speed of 10 $\mathrm{m} / \mathrm{s}$ , Lance Armstrong starts going downhill with an acceleration of magnitude 1.2 $\mathrm{m} / \mathrm{s}^{2} .$ The descent takes 10.0 $\mathrm{s}$ . What can you determine about Lance's motion using these data? What assumptions did you make?

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Oswaldo Jiménez

Numerade educator

In Exercises $27-42$ , evaluate the function at each specified value of the independent variable and simplify. $$ \begin{array}{l}{f(x)=|x|+4} \\ {\text { (a) } f(4)} & {\text { (b) } f(-4) \quad \text { (c) } f(t)}\end{array} $$

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C D

Numerade educator

Shown are graphs of the position functions of two runners, A and B, who run a 100 meter race and finish in a tie. (a) Describe and compare how the runners run the race. (b) At what time is the distance between the runners the greatest? (c) At what time do they have the same velocity?

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Hubert Agamasu

Numerade educator

(II) Estimate the kinetic energy of the Earth with respect to the Sun as the sum of two terms, $(a)$ that due to its daily rotation about its axis, and $(b)$ that due to its yearly revolution about the Sun. [Assume the Earth is a uniform sphere with $mass = 6.0 \times 10^{24} kg$, $radius = 6.4 \times 10^6 m$, and is $1.5 \times 10^8 km$ from the Sun.]

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Prabhat Tyagi

Numerade educator

How many hybrid orbitals do we use to describe each molecule? a. N2O5 b. C2H5NO (4 C-H bonds and one O-H bond) c. BrCN (no formal charges)

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Christopher Dzorkpata

Numerade educator

An object is hung from a spring balance attached to the ceiling of an elevator cab. The balance reads 65 $\mathrm{N}$ when the cab is standing still. What is the reading when the cab is moving upward (a) with a constant speed of 7.6 $\mathrm{m} / \mathrm{s}$ and $(\mathrm{b})$ with a speed of 7.6 $\mathrm{m} / \mathrm{s}$ while decelerating at a rate of 2.4 $\mathrm{m} / \mathrm{s}^{2} ?$

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INSTANT ANSWER

As shown in the accompanying figure, a child with mass $34 \mathrm{kg}$ is seated on a smooth (frictionless) playground slide that is inclined at an angle of $27^{\circ}$ with the horizontal. How much force does the child exert on the slide, and how much force must be applied in the direction of $\mathbf{P}$ to prevent the child from sliding down the slide? Take the acceleration due to gravity to be $9.8 \mathrm{m} / \mathrm{s}^{2}$

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Albert Tres

Numerade educator

Incoming students at a certain law school have an average LSAT (Law School Aptitude Test) score of 163 and an $S D$ of 8 . Tomorrow, one of these students will be picked at random. You have to guess the score now; the guess will be compared with the actual score, to see how far off it is. Each point off will cost a dollar. For example, if the guess is 158 and the score is really $151,$ you will have to pay $\$ 7 .$ . (a) Is the best guess $150,163,$ or 170$?$ (b) You have about 1 chance in 3 to lose more than $\longrightarrow$ Fill in the blank. Options: $\$ 1, \$ 8, \$ 20 .$ (LSAT scores range from 120 to 180 ; the average across all test-takers is about 150 and the SD is about $9 .$ The test is re-normed from time to time, the data are for $2005 . )$

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Emily M.