On a scale drawing with a scale of 1/80, the height of a building is 9.75 inches. How tall is the actual building?

A newspaper article about the results of a poll states: "In theory, the results of such a poll, in 99 cases out of 100 should di

frutty [35]

Answer:

The sample size suggested by this statement is of at least 4145.

Step-by-step explanation:

This statement states that the 99% confidence interval has a margin of error of 2 percentage points.

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 is:

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

99% confidence level:

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

Find the sample size suggested by this statement.

The sample size is at least n.

n is found when M = 0.02.

We don't know the true proportion, so we use $\pi = 0.5$ , which is when the largest sample size will be needed.

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

$0.02 = 2.575\sqrt{\frac{0.5*0.5}{n}}$

$0.02\sqrt{n} = 2.575*0.5$

$\sqrt{n} = \frac{2.575*0.5}{0.02}$

$(\sqrt{n})^{2} = (\frac{2.575*0.5}{0.02})^{2}$

$n = 4144.14$

Rounding up

The sample size suggested by this statement is of at least 4145.

5 0

3 years ago

Please help me :)

Goryan [66]

Answer:

Part B= (7.5 years, 2.25ish dollars) or about (7,2)

Step-by-step explanation:

im sorry i couldn't answer part b

8 0

3 years ago

Emily sent 60 texts so far this week. What is 20%of the total number of text messages she is allowed in one week

Rina8888 [55]

Answer:

so we should find the %20 of 60

60.%20=12

Step-by-step explanation:

the answer is 12

hope it helps

6 0

3 years ago

The population of the world was 7.1 billion in 2013, and the observed relative growth rate was 1.1% per year. A) Estimate how lo

VLD [36.1K]

Answer:

A) 63.36 years.

B) 100.42 years.

Step-by-step explanation:

We have been given that the population of the world was 7.1 billion in 2013, and the observed relative growth rate was 1.1% per year.

A) Since we know that population increases exponentially, therefore we will use our given information to form an exponential model for population increase and then we will solve for the time by which our population will be double.

$P(t)=7.1(1.011)^{t}$