A personnel director in a particular state claims that the mean annual income is greater in one of the state's counties (county A) than it is in another county (county B). In County A, a random sample of 12 residents has a mean annual income of \( \$ 40,600 \) and a standard deviation of \( \$ 8100 \). In County B , a random sample of 10 residents has a mean annual income of \( \$ 38,000 \) and a standard deviation of \( \$ 5500 \). At \( \alpha=0.005 \), answer parts (a) through (e). Assume the population variances are not equal. If convenient, use technology to solve the problem. (a) Identify the claim and state \( \mathrm{H}_{0} \) and \( \mathrm{H}_{\mathrm{a}} \). Which is the correct claim below? A. "The mean annual income in county A is less than in county B." C. "The mean annual income in county A is greater than in county B." D. "The mean annual incomes in counties A and B are equal."

2. What is your first impression of the narrator? Is he trying to convince the reader of something? What is it? 3. Generally speaking, how does the narrator feel about the old man? What exactly is it about the old man that bothers the narrator? Why? How often does the narrator mention this "thing" in the story? 4. What does the narrator tell us he does every night? Why? 5. How does the narrator feel immediately after he commits the murder? Do his feelings change? If so, how and why? 4

2. \( -17+4 x=11 \)

Cuál es la velocidad del sonido en el aire a una temperatura de \( 20^{\circ} \) y \( 68^{\circ} \)

5. \( a m-2 b m-3 a n+6 b n \) 6. \( 4 a^{2} x-5 a^{2} y+15 b y-12 b x \) 7. \( m^{2} p^{2}-3 n p^{2}+m^{2} z^{2}-3 n z^{2} \) 8. \( 5 m^{2} n+5 m p^{2}+n^{2} p^{2}+m n^{3} \) 9. \( 3 a-2 b-2 b y^{4}+3 a y^{4} \) 10. \( 2 m x^{4}+3 n x^{4}+10 m+15 n \) 11. \( b m^{2}+b y^{2}-c m^{2}-c y^{2} \) 12. \( x^{3}-15-5 x+3 x^{2} \)

La figura adjunta muestra la parábola correspondiente a la función \( f(x)=x^{2}-8 x+15 \). ¿Cuáles son las coordenadas del vértice P ? a) \( (1,-4) \) b) \( (3,-5) \) c) \( (4,-1) \) d) \( (15,-4) \)