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3 years ago

Find the solutions for x when y is equal to 0. y = x2 - 3x -18

Mathematics

1 answer:

denis23 [38]3 years ago

3 0

Y = x² - 3x - 18

When y = 0,

x² - 3x - 18 = 0

<span>(x + 3)(x - 6) = 0
</span>
x = -3 or x = 6

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How do I divide pi by 1000?

Leokris [45]

Just as you would do it with any other number.

Write out some of it, then move the decimal point 3 places this way <=== .

Some of pi : 3.14159

Divide by 1,000 : 0.00314159

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3 years ago

An SRS of 350 high school seniors gained an average of x¯=21 points in their second attempt at the SAT Mathematics exam. Assume

Lynna [10]

Answer:

a) $21-2.58\frac{52}{\sqrt{350}}=13.83$

$21+2.58\frac{52}{\sqrt{350}}=28.17$

So on this case the 99% confidence interval would be given by (13.83;28.17)

b) $ME=2.58\frac{52}{\sqrt{350}}=7.17$

c) $ME=2.58\frac{52}{\sqrt{100}}=13.42$

d) D. Decreasing the sample size increases the margin of error, provided the confidence level and population standard deviation remain the same.

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".

Part a

$\bar X=21$ represent the sample mean

$\mu$ population mean (variable of interest)

$\sigma=52$ represent the population standard deviation

n=350 represent the sample size

99% confidence interval

The confidence interval for the mean is given by the following formula:

$\bar X \pm z_{\alpha/2}\frac{\sigma}{\sqrt{n}}$ (1)

Since the Confidence is 0.99 or 99%, the value of $\alpha=0.01$ and $\alpha/2 =0.005$ , and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-NORM.INV(0.005,0,1)".And we see that $z_{\alpha/2}=2.58$

Now we have everything in order to replace into formula (1):

$21-2.58\frac{52}{\sqrt{350}}=13.83$

$21+2.58\frac{52}{\sqrt{350}}=28.17$

So on this case the 99% confidence interval would be given by (13.83;28.17)

Part b

The margin of error is given by:

$ME=2.58\frac{52}{\sqrt{350}}=7.17$

Part c

The margin of error is given by:

$ME=2.58\frac{52}{\sqrt{100}}=13.42$

Part d

As we can see when we reduce the sample size we increase the margin of error so the best option for this case is:

D. Decreasing the sample size increases the margin of error, provided the confidence level and population standard deviation remain the same.

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3 years ago

Beginning inventory: $14,320 Merchandise Purchases: $7,880 Goods available for sale: (a) Ending inventory: $11,250 Cost of goods

VikaD [51]

Answer:

$22,200

$10,950

Step-by-step explanation:

Goods available for sale = beginning inventory + Merchandise Purchases

$14,320 + $7,880 = $22,200

Ending inventory = goods available for sale - ending inventory

$22,200 - $11,250 = $10,950

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3 years ago

Urgent!!!!!In a class of students, the following data table summarizes the gender of the students

Setler79 [48]

Answer:

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Step-by-step explanation:

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3 years ago

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WITCHER [35]

The LCM this question is 13 and 29

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3 years ago

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