Determine the scale factor for triangle $ABC$ to triangle $A'B'C'$.

A) $10$; B) $20$; C) $2$; D) $\dfrac{1}{2}$.

Silicon forms a series of compounds that is analogous to alkanes and has the general formula $\mathrm{Si}_{\mathrm{n}} \mathrm{H}_{2 \mathrm{n}+2}$. The first of these compounds is silane, $\mathrm{SiH}_4$, which is used in the electronics industry to produce thin ultrapure silicon films. $\mathrm{SiH}_4(\mathrm{~g})$ is somewhat difficult to work with because it is pyrophoric at room temperature-meaning that it bursts into flame spontaneously.

(a) Write an equation for the combustion of $\mathrm{SiH}_4(\mathrm{~g})$. (The reaction is analogous to hydrocarbon combustion, and $\mathrm{SiO}_2$ is a solid under standard conditions. Assume the water produced will be a gas.)

(b) Use the data from Appendix $\mathrm{E}$ to calculate $\Delta S^{\circ}$ for this reaction.

(c) Calculate $\Delta G^{\circ}$ and show that the reaction is spontaneous at $25^{\circ} \mathrm{C}$.

(d) Compare $\Delta G^{\circ}$ for this reaction to the combustion of methane. Are the reactions in these two exercises enthalpy or entropy driven? Explain.

Professor Grant Alexander wanted to find a linear model that relates the number of hours a student plays video games each week, h, to the cumulative grade-point average, G, of the student. He obtained a random sample of 10 full-time students at his college and asked each student to disclose the number of hours spent playing video games and the student’s cumulative grade-point average. "

$$\begin{matrix} \text{Hours of} & \text{Grade-point}\\ \text{Video Games} & \text{Average, $G$}\\ \text{per Week, $h$} & \text{ }\\ \hline \text{0} & \text{3.49}\\ \text{0} & \text{3.05}\\ \text{2} & \text{3.24}\\ \text{3} & \text{2.82}\\ \text{3} & \text{3.19}\\ \text{5} & \text{2.78}\\ \text{8} & \text{2.31}\\ \text{8} & \text{2.54}\\ \text{10} & \text{2.03}\\ \text{12} & \text{2.51}\\ \end{matrix}$$

Predict the grade-point average of a student who plays video games for 8 hours each week.

Maximize $C=7 x+2 y$ with the constraints

$$\left\{\begin{array}{r} x+3 y \leq 108 \\ 7 x+4 y \leq 280 \end{array}\right.$$

In paragraph $67$, Hemingway writes, “Krebs looked at the bacon fat hardening on his plate.” What does that image suggest about Krebs? How does it contribute to the story? In paragraph $85$, Hemingway writes, “Krebs felt sick and vaguely nauseated.” How would you explain the causes of his unease?

Di qué hicieron las siguientes personas durante su excursión al aire libre.
Elena / divertirse al aire libre

How does rational ignorance discourage voting?

A rabbit population doubles in size every 18 months. If there are 10,000 rabbits at $t=0$, when will the population reach 100,000?

What is the minimum potential difference applied to an x-ray tube if x-rays of wavelength 0.250 nm are produced?

Find a constant b such that h is continuous at x = 2, where

$$h ( x ) = \left\{ \begin{array} { l l } { x + 1 } & { \text { for } | x | < 2 } \\ { b - x ^ { 2 } } & { \text { for } | x | \geq 2 } \end{array} \right.$$

With this choice of b, find all points of discontinuity.

A researcher wants to know if the octane level of gasoline affects the gas mileage of a car. She randomly selects 10 cars and puts 5 gallons of 87-octane gasoline in the tank. On a closed track, each car is driven at 50 miles per hour until it runs out of gas. The experiment is repeated, with each car getting 5 gallons of 92-octane gasoline. The miles per gallon for each car are then computed. The results are shown. Would you recommend purchasing 92 octane? Why or why not?

$$\begin{matrix} \text{87 Octane} & \text{92 Octane} & \text{87 Octane} & \text{92 Octane}\\ \text{18.0} & \text{18.5} & \text{23.4} & \text{22.8}\\ \text{23.2} & \text{23.1} & \text{23.1} & \text{23.5}\\ \text{31.5} & \text{31.9} & \text{19.0} & \text{19.5}\\ \text{24.9} & \text{26.7} & \text{26.8} & \text{26.2}\\ \text{24.1} & \text{25.1} & \text{31.8} & \text{30.7}\\ \end{matrix}$$

Refer to earlier exercise. The gas mileage (in miles per gallon) for each of the seven automobiles driven by randomly chosen sales representatives during the week prior to the installation of governors and during the following week is shown in the accompanying table.

$$\begin{array}{l|ccccccc} \hline \text { Salesperson } & \text { A } & \text { B } & \text { C } & \text { D } & \text { E } & \text { F } & \text { G } \\ \hline \text { Before } & 25 & 21 & 27 & 23 & 19 & 18 & 20 \\ \hline \text { After } & 26 & 24 & 26 & 25 & 24 & 22 & 23 \\ \hline \end{array}$$

a. Can you infer that the usage of governors tends to boost the median gas mileage for Gamma Corporation's sales representatives using the Wilcoxon signed-rank test at the $5 \%$ level of significance? b. Compare your conclusion of part a with the result of the hypothesis test that was performed (using the $t$ distribution) in earlier exercise.

The surface of an iron component is to be hardened by carbon. The diffusion coefficient of carbon in iron at $1000^\circ C$ is given to be $3 \times 10^{–11} m^2/s.$ If the penetration depth of carbon in iron is desired to be 1.0 mm. the hardening process must take at least (a) 1.10 h (b) 1.47 h (c) 1.86 h (d) 2.50 h (e) 2.95 h

Which area of the brain regulates emotions and behavioral drives?