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3 years ago

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If stratified random sampling with proportional allocation is used to select a sample of 25 high schools, how many would be sel

ected from the stratum with a percent-free-lunch value of 40 less than or equals x?

1 answer:

gregori [183]3 years ago

7 0

Answer:

02 High Schools would be selected from the stratum with a percent-free-lunch value of 40 less than or equals x.

Step-by-step explanation:

As the sample size needed is 25 and total schools are 100 so this indicate 1 school in each 4 schools is to be selected. This is given as

$n=\frac{n_{total}}{n_{sample}}\\n=\frac{100}{25}\\n=4$

Now as the schools with percent free lunch are 8 so now

$n=\frac{n_{total}}{n_{sample}}\\n=\frac{8}{2}\\n=2$

So only 2 schools will be selected in this regard.

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Determine each of the following.

castortr0y [4]

Answer:

(a) $\{1,2,3,4,5,6,7,8,9,10\}$

(b) 10

(c) $\{\}$

(d) 0

(e) 1024

Step-by-step explanation:

(a)

A = {x ∈ Z | 0 < x, x² ≤ 100}

We need to find all the elements of given set.

The given conditions are

$0$ ... (1)

$x^2\leq 100$

Taking square root on both sides.

$-\sqrt{100}\leq x\leq \sqrt{100}$

$-10\leq x\leq 10$ .... (2)

Using (1) and (2) we get

$0$

Since x ∈ Z,

$A=\{1,2,3,4,5,6,7,8,9,10\}$

(b)

We need to find the value of | {x ∈ Z | 0 < x, x² ≤ 100}| or |A|. It means have to find the number of elements in set A.

$|A|=10$

| {x ∈ Z | 0 < x, x² ≤ 100}| = 10

(c)

B = {x ∈ Z | x > 10, x² ≤ 100}

We need to find all the elements of given set.

The given conditions are

$x>10$ ... (3)

$x^2\leq 100$

It means

$-10\leq x\leq 10$ .... (4)

Inequality (3) and (4) have no common solution, so B is null set or empty set.

$B=\{\}$

(d)

We need to find the value of |{x ∈ Z | x > 10, x² ≤ 100}| or |B|. It means have to find the number of elements in set B.

$|B|=0$

|{x ∈ Z | x > 10, x² ≤ 100}| = 0

(e)

We need to find the value of | P(A) |. P(A) is the power set of set A.

Number of elements of a power set is

$N=2^n$

where, n is the number of elements of set A.

We know that the number of elements of set is 10. So the value of |P(A)| is

$|P(A)|=2^{10}$

$|P(A)|=1024$

Therefore |P(A)|=1024.

7 0

3 years ago

Please help. <br>I will mark brainliest

telo118 [61]

Answer: the x-intercept is (-10,0), the y-intercept is (0,45/2)

Explanation:

First, we need to determine the function describing the line.

From the table, it is obvious that the y values increase by 9 every increase of 4 of the x values. So, the slope is 9/4 and the function looks like this:

$y = m x+ b = \frac{9}{4}x + b$

with the y-intercept (or bias) b still unknown. This can be determined by using one of the point from the table, like so:

$-18 = \frac{9}{4}\cdot 2+b\\\implies b = -18 -\frac{9}{2}=\frac{45}{2}\\y = \frac{9}{4}x+\frac{45}{2}$

The above function form makes it easy to read off the y-intercept, which is (0,45/2) or (0,22.5). The x-intercept is obtained by setting y = 0 and solving for x:

$y = \frac{9}{4}x+\frac{45}{2}\\0 = \frac{9}{4}x+\frac{45}{2}\\-\frac{45}{2}=\frac{9}{4}x\\x = -10$

The x-intercept is (-10,0)

5 0

3 years ago

Read 2 more answers

Which substance is a mixture?<br> salt<br> gasoline<br> aluminum<br> carbon dioxide

pogonyaev

First, we must understand why the three other choices are not mixtures. Salt is a compound made from elements Sodium and Chlorine. Aluminum is an element. Carbon dioxide is also a compound composed of Carbon and Oxygen. Now, gasoline. is substance made from refined crude oils (or hydrocarbons). As a matter of fact, gasoline is an example of a homogenous mixture. Thus, amongst the choices, the mixture would be gasoline<span>. </span>

5 0

3 years ago

Read 2 more answers

What is x -2=-11? Algebra

neonofarm [45]

Answer:

-9

Step-by-step explanation:

you'd add 2 to the -11 which would equal -9 and leave you with x=-9

8 0

3 years ago

Read 2 more answers

Suppose that birth weights are normally distributed with a mean of 3466 grams and a standard deviation of 546 grams. Babies weig

Anon25 [30]

Answer:

3.84% probability that it has a low birth weight

Step-by-step explanation:

Problems of normally distributed samples are solved using the z-score formula.

In a set with mean $\mu$ and standard deviation $\sigma$ , the zscore of a measure X is given by:

$Z = \frac{X - \mu}{\sigma}$

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

In this problem, we have that:

$\mu = 3466, \sigma = 546$

If we randomly select a baby, what is the probability that it has a low birth weight?

This is the pvalue of Z when X = 2500. So

$Z = \frac{X - \mu}{\sigma}$

$Z = \frac{2500 - 3466}{546}$

$Z = -1.77$

$Z = -1.77$ has a pvalue of 0.0384

3.84% probability that it has a low birth weight

3 0

3 years ago