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aleksklad [387]

2 years ago

11

Out of the 25 students in Mrs. Coulter's class, 15 are girls. In the school there are 390 boys. If the ratio of boys to students

in Mrs. Coulter's class is proportional to the ratio of the number of boys in the school to the total number of students in the school, how many students are at the school?

2 answers:

GREYUIT [131]2 years ago

6 0

Answer:

975 students

Step-by-step explanation:

This is a dense question. Let's look at it piece by piece:

1. The ratio of boys to students in the class is 10/25. If there are 25 students and 15 girls, that leaves 10 boys.

2. The question says that the ratio is in proportion of boys to total students in the school. "In proportion" in this case means that if we convert 10/25 to a fraction with numerator 390, the denominator is the amount of students in school.

3. 10x39=390. What you do the numerator you must do to the denominator: 25x39=975.

4. This means 975 students go to the school.

kotegsom [21]2 years ago

6 0

That is correct I would say!
Ty for the explanation

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(-18x^2+12x-2)*(x^3+12x^2+48x+64)

prohojiy [21]

<h2>Answer:</h2>

-18x^5-204x^4-722x^3-600x^2+672x-128

<h2>Explanation:</h2>

$( - 18 {x}^{2} + 12x - 2)$

$( {x}^{3} + 12 {x}^{2} + 48x + 64)$

There are multiple ways to solve this for example the foil method or the box method. I prefer to do the box method.

First we are going to set it up

After we set it up we have to solve it so first we are going to multiply

${x}^{3} \times - 18 {x}^{2} = - 18 {x}^{5}$

We have to add the exponent

$- 18 {x}^{2} \times 12 {x}^{2} = - 216 {x}^{4}$

$- 18 {x}^{2} \times 48x = - 864 {x}^{3 } \\ - 18{x}^{2} \times 64 = - 1152 {x}^{2} \\ 12x \times {x}^{3} = 12 {x}^{4} \\ 12x \times 12 {x}^{2} = 144 {x}^{3}$

$12x \times 48x = 576 {x}^{2} \\ 12x \times 64 = 768x$

$- 2 \times {x}^{3} = - 2 {x}^{3} \\ - 2 \times 12 {x}^{2} = - 24 {x}^{2} \\ - 2 \times 48x = - 96x \\ - 2 \times 64 = - 128$

Now we have to add them

-18x^5 stays because there is nothing to add to

Now we add the rest

$-216 {x}^{4} + 12 {x}^{4} = - 204 {x}^{4}$

$- 864 {x}^{3} + 144 {x}^{3} + - 2 {x}^{3} = - 722 {x}^{3}$

$768x - 96x = 672x$

And -128 stays the same

$- 1152 {x}^{2} + 576 {x}^{2} - 24 {x}^{2} = - 600 {x}^{2}$

The answer is

-18x^5-204x^4-722x^3-600x^2+672x-128

5 0

4 years ago

Of 580580 samples of seafood purchased from various kinds of food stores in different regions of a country and genetically compa

Lubov Fominskaja [6]

Answer:

a) The 99% confidence interval would be given (0.204;0.296).

b) We have 99% of confidence that the true population proportion of all seafood sold in the country that is mislabeled or misidentified is between (0.204;0.296).

c) No that's not true. Because the necessary assumptions and conditions for the confidence interval for the proportion are satisifed, so then we can use inferential statistics to interpret the interval to the population of interest.

Step-by-step explanation:

Part a

Data given and notation

n=580 represent the random sample taken

X represent the seafood sold in the country that is mislabeled or misidentified by the people

$\hat p=0.25$ estimated proportion of seafood sold in the country that is mislabeled or misidentified by the people

$\alpha=0.01$ represent the significance level (no given, but is assumed)

p= population proportion of seafood sold in the country that is mislabeled or misidentified by the people

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".

The margin of error is the range of values below and above the sample statistic in a confidence interval.

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

The population proportion have the following distribution

$p \sim N(p,\sqrt{\frac{\hat p(1-\hat p)}{n}})$

The confidence interval would be given by this formula

$\hat p \pm z_{\alpha/2} \sqrt{\frac{\hat p(1-\hat p)}{n}}$

For the 99% confidence interval the value of $\alpha=1-0.99=0.01$ and $\alpha/2=0.005$ , with that value we can find the quantile required for the interval in the normal standard distribution.

$z_{\alpha/2}=2.58$

And replacing into the confidence interval formula we got:

$0.25 - 2.58 \sqrt{\frac{0.25(1-0.25)}{580}}=0.204$

$0.25 + 2.58 \sqrt{\frac{0.25(1-0.25)}{580}}=0.296$

And the 99% confidence interval would be given (0.204;0.296).

Part b

We have 99% of confidence that the true population proportion of all seafood sold in the country that is mislabeled or misidentified is between (0.204;0.296).

Part c

A government spokesperson claimed that the sample size was too small, relative to the billions of pieces of seafood sold each year, to generalize. Is this criticism valid?

No that's not true. Because the necessary assumptions and conditions for the confidence interval for the proportion are satisifed, so then we can use inferential statistics to interpret the interval to the population of interest.

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4 years ago

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leonid [27]

Answer:

a c d i think those are answers

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Which sequence of transformations takes figure B to its image B'?

marin [14]

Answer:

D. a reflection in the y-axis, followed by a counterclockwise rotation of 270 about the origin

Step-by-step explanation:

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I am delighted to assist you anytime my friend.

5 0

4 years ago

3 Which of the following numbers would be found

vesna_86 [32]

Answer:

C is the answer

Step-by-step explanation:

35+1=36

35-------------36

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3 years ago

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