A boy's mother was 32 years old when he was born. Let a represent the boy's age and m represent the mother's age.

Exercise 6.13 presents the results of a poll evaluating support for the health care public option in 2009, reporting that 52% of

sleet_krkn [62]

Answer:

A sample size of 6755 or higher would be appropriate.

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 level of $1-\alpha$ , 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 $1 - \frac{\alpha}{2}$ .

The margin of error M is given by:

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

90% confidence level

So $\alpha = 0.1$ , z is the value of Z that has a pvalue of $1 - \frac{0.1}{2} = 0.95$ , so $Z = 1.645$ .

52% of Independents in the sample opposed the public option.

This means that $p = 0.52$

If we wanted to estimate this number to within 1% with 90% confidence, what would be an appropriate sample size?

Sample size of size n or higher when $M = 0.01$ . So

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

$0.01 = 1.645\sqrt{\frac{0.52*0.48}{n}}$

$0.01\sqrt{n} = 0.8218$

$\sqrt{n} = \frac{0.8218}{0.01}$

$\sqrt{n} = 82.18$

$\sqrt{n}^{2} = (82.18)^{2}$

$n = 6754.2$

A sample size of 6755 or higher would be appropriate.

3 0

2 years ago

What is the exact value of cos(11pi/21)cos(pi/7)-sin(11pi/21)sin(pi/7)?

Anika [276]

Answer:

B

Step-by-step explanation:

-1/2

7 0

2 years ago

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The grade point averages (GPA) for 12 randomly selected college students are shown on the right. Complete parts (a) through (c)

Ilya [14]

Answer:

$\bar X =\frac{2.3+3.1+2.8+1.7+0.9+4+2.1+1.2+3.6+0.2+2.4+3.2}{12}=2.29$

$s=1.09$

Step-by-step explanation:

For this case we have the following data given:

2.3 3.1 2.8

1.7 0.9 4.0

2.1 1.2 3.6

0.2 2.4 3.2

Since the data are assumedn normally distributed we can find the standard deviation with the following formula:

$\sigma =\sqrt{\frac{\sum_{i=1}^n (X_i -\bar X)^2}{n}}$

And we need to find the mean first with the following formula:

$\bar X = \frac{\sum_{i=1}^n X_i}{n}$

And replacing we got:

$\bar X =\frac{2.3+3.1+2.8+1.7+0.9+4+2.1+1.2+3.6+0.2+2.4+3.2}{12}=2.29$

And then we can calculate the deviation and we got:

$s=1.09$

7 0

2 years ago

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Suppose a spider was able to create one thread that would extend from the top-right back corner of a room to the bottom-left fro

NNADVOKAT [17]

Answer:

d^2 = 30^2 + 12^2

e^2 = d^2 + 8^2

e^2 = 30^2 + 12^2 + 8^2

e = √(30^2 + 12^2 + 8^2) = 33.3 ft

7 0

2 years ago

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Help please this my second time posting this please help

Nesterboy [21]

Answer:

x = √30

Step-by-step explanation:

From small triangle BDC:

using Pythagorean theorem

CB² = BD² + DC²

x² = BD² + 3²

Fron triangles BDC and ADB.

ΔBDC has long leg BD and short leg DC.

ΔADB has long leg AD and shirt leg BD.

AD : BD = BD : DC

7 : BD = BD : 3

7*3 = BD*BD

BD² = 7*3 = 21

x² = BD² + 3² = 21+9 = 30

x² = 30

x = √30

4 0

2 years ago