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2 years ago

A bag contains 12 red marbles The ratio of red marbles to blue marbles is 4:3?

Mathematics

1 answer:

Ostrovityanka [42]2 years ago

8 0

There are 9 blue marbles.

Step-by-step explanation:

12÷4=3

3×3=9

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The radius of a circle is 10 cm. Find its circumference in terms of pi

sergejj [24]

Answer:

20 pi is the correct answer

5 0

2 years ago

Jessica's Furniture Store manager is trying to figure out how much to charge for an armchair that just arrived. The chair was pu

VARVARA [1.3K]

Answer: The manager should sell the chair for $1740.

Step-by-step explanation:

45% of 1200 Solve this to find the amount increase

0.45 * 1200 = 540 Now add this amount to find the price.

$1200 + $540 = $1740

or you could do it this way

100% + 45% = 145%

145% of 1200 =?

1.45 * 1200 = 1740

3 0

3 years ago

Nitrates are groundwater contaminants derived from fertilizer, septic tank seepage and other sewage. Nitrate poisoning is partic

o-na [289]

Answer:

a) $n=\frac{0.5(1-0.5)}{(\frac{0.02}{1.96})^2}=2401$

And rounded up we have that n=2401

b) $n=\frac{0.07(1-0.07)}{(\frac{0.02}{1.96})^2}=625.22$

And rounded up we have that n=626

And we see that if we have previous info about p the sample size varies a lot.

Step-by-step explanation:

Previous concepts

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".

Solution to the problem

In order to find the critical value we need to take in count that we are finding the interval for a proportion, so on this case we need to use the z distribution. Since our interval is at 95% of confidence, our significance level would be given by $\alpha=1-0.95=0.05$ and $\alpha/2 =0.025$ . And the critical value would be given by:

$z_{\alpha/2}=-1.96, z_{1-\alpha/2}=1.96$

Part a

The margin of error for the proportion interval is given by this formula:

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

And on this case we have that $ME =\pm 0.02$ and we are interested in order to find the value of n, if we solve n from equation (a) we got:

$n=\frac{\hat p (1-\hat p)}{(\frac{ME}{z})^2}$ (b)

Since we don't have prior information about the population proportion we can use ase estimator $\hat p =0.5$ . And replacing into equation (b) the values from part a we got:

$n=\frac{0.5(1-0.5)}{(\frac{0.02}{1.96})^2}=2401$

And rounded up we have that n=2401

Part b

For thi case the estimator for p is $\hat p =0.07$

$n=\frac{0.07(1-0.07)}{(\frac{0.02}{1.96})^2}=625.22$

And rounded up we have that n=626

And we see that if we have previous info about p the sample size varies a lot.

4 0

3 years ago

Mai's water bottle had 24 ounces in it. After she drank x

snow_tiger [21]

Answer:

Option B and C is correct

Step-by-step explanation:

<h3><u>Given</u>;</h3>

Priya has 5 pencils, each x inches in length.
Total length = 34.5 inches.

Now,

5 times x = 34.5

So,

5x = 34.5

34.5 ÷ 5 = x

Thus, 5x = 34.5 and 34.5 ÷ 5 = x are the answer

<u>-TheUnknownScientist 72</u>

5 0

2 years ago

Help! what’s the answer. I looked it up but it’s not right too many different answers

Ne4ueva [31]

7x+2y=-17

steps:
x=2x + 5x
y=3y - y
sum=-5 -12

6 0

3 years ago