Mathematics, 01.10.2019 06:30 maryam2863

Of 150 adults selected randomly from one town, 30 of them smoke. construct a 99% confidence interval for the true percentage of all adults in the town that smoke.

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Answer from: nyed5789

The 99% confidence interval for the true percentage of all adults in the town that smoke is (0.1159, 0.2841).

Step-by-step explanation:

In a sample with a number n of people surveyed with a probability of a success of $\pi$ , and a confidence interval $1-\alpha$ , we have the following confidence interval of proportions.

$\pi \pm z\sqrt{\frac{\pi(1-\pi)}{n}}$

In which

z is the zscore that has a pvalue of $1 - \frac{\alpha}{2}$ .

For this problem, we have that:

Of 150 adults selected randomly from one town, 30 of them smoke. This means that $n = 150, p = \frac{30}{150} = 0.2$

99% confidence interval

So $\alpha = 0.01$ , z is the value of Z that has a pvalue of $1 - \frac{0.01}{2} = 0.995$ , so Z = 2.575 .

The lower limit of this interval is:

$\pi - z\sqrt{\frac{\pi(1-\pi)}{n}} = 0.20 - 2.575\sqrt{\frac{0.20*0.80}{150}} = 0.1159$

The upper limit of this interval is:

$\pi + z\sqrt{\frac{\pi(1-\pi)}{n}} = 0.20 + 2.575\sqrt{\frac{0.20*0.80}{150}}{119}} = 0.2841$

The 99% confidence interval for the true percentage of all adults in the town that smoke is (0.1159, 0.2841).

Answer from: Quest

the solution is the point $(1,-3)$

step-by-step explanation:

we have

$3x-y=6$ > equation a

$y=x-4$ > equation b

adds equation a and equation b

$3x-y=6\\y=x--y+y=6+x-4\\3x=2+x\\3x-x=2\\2x=2\\x=1$

substitute the value of x in equation b to find the value of y

$y=(1)-4=-3$

the solution is the point $(1,-3)$

Answer from: Quest

la parábola es el lugar

geométrico en el cual los puntos tienen una distancia idéntica, equidistantes,

de un punto denominado foco, f, y una recta denominada directriz

el radio vector de una

parábola es el segmento que existe entre un punto cualquiera y el foco.

por la ecuación se observa

que la parábola abre hacia la derecha, por lo cual podemos usar las siguientes fórmulas

la ecuación ordinaria de la

parábola es y^2 = 4px, donde p es la longitud desde el vértice de la parábola al

foco.

la fórmula de la directriz

es x + p = 0

resolviendo:

y^2-9x = 0

y^2 = 9x

4p = 9, entonces p = 9/4

entonces el foco tendrá la

coordenada f(9/4,0)

la directriz vendrá

expresada por

x + p = 0

x = -p

x = -9/4

el problema indica que la

ordenada es igual a 6, entonces

(6)^2=9x

x = 36/9

x = 4

entonces el punto al cual

hay que obtener la distancia será p(4,6)

calculando se tendrá: pf =

pf = 6,25 u

ver más en -

step-by-step explanation:

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Of 150 adults selected randomly from one town, 30 of them smoke. construct a 99% confidence interval...