The SAT exam is used in admissions decisions by many four-year colleges and universities. In 2006, The College Board carried out a study of 6,498 SAT essays that were selected at random from the more than 1.4 million SAT exams taken in the 2005 - 2006 academic year. For this sample of essays, 15% were written in cursive and 85% were printed in block letters. The results showed that the average score for essays written in cursive was higher than the average score for essays that were printed.
A. is this study an observational study or an experiment? Explain your answer.
B. is it reasonable to conclude that writing the essay in cursive was the cause of the higher scores? Explain your answer?

Answer:

$300

Step-by-step explanation:

Let [tex]x[/tex] be the original price.

[tex]x \times (1-0.04)=288[/tex]

[tex]0.96x=288[/tex]

[tex]x=\frac{288}{0.96}[/tex]

[tex]x=300[/tex]

Answer:

$300

Step-by-step explanation:

If it was a 4% reduction then we get:

[tex]x*0.96=288\\[/tex]

Divide both sides by 0.96

[tex]x=300[/tex]

The original suit price was $300

Answer:

Brainleist :)

Step-by-step explanation:

120 dollars for 4 hours of labor

120/4 dollars for 1 hour of labor

B) 30 dollars for 1 hour of labor

answe:

B) 30 dollars for 1 hour of labor

Step-by-step explanation:

120 dollars for 4 hours of labor

120/4 dollars for 1 hour of labor

important messagee:

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♡ Thank you for ur time 。 ♡

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Answer: b

Explanation:

The -2 outside of the parentheses means it’s at y=-2 and the -4 inside the parentheses means it’s at x= 4 because it’s always the opposite

Answer:

-3

Step-by-step explanation:

every sequence goes down by -3

Answer:

take away 3. the common difference is 3

Step-by-step explanation:

take away 3

Answer:

it’s C

Step-by-step explanation:

No, the vertices of the image and pre-image do not correspond

No, the vertices of the image and pre-image do not correspond, Micaela tried to rotate the square 180° about the origin. Hence, option C is correct.

A figure can be rotated by 90 degrees clockwise by rotating each vertex of the figure 90 degrees clockwise about the origin.

Let's take the vertices of a square with points at (+1,+1), (-1,+1), (-1,-1), and (+1,-1), centered at the origin, can be found in the following positions after rotation:

Micaela's rotation must be accurate if it led to the same points. Her rotation is incorrect if the points are different, though.

It is impossible to tell if Micaela's rotation is accurate without more details or a diagram.

Thus, option C is correct.

For more information about rotation about the origin, click here:

https://brainly.com/question/30198965

#SPJ7

Answer:

The 88% confidence interval for the proportion of defectives today is (0.053, 0.123)

Step-by-step explanation:

In a sample with a number n of people surveyed with a probability of a success of [tex]\pi[/tex], and a confidence level of [tex]1-\alpha[/tex], we have the following confidence interval of proportions.

[tex]\pi \pm z\sqrt{\frac{\pi(1-\pi)}{n}}[/tex]

In which

z is the zscore that has a pvalue of [tex]1 - \frac{\alpha}{2}[/tex].

For this problem, we have that:

[tex]n = 160, \pi = \frac{14}{160} = 0.088[/tex]

88% confidence level

So [tex]\alpha = 0.12[/tex], z is the value of Z that has a pvalue of [tex]1 - \frac{0.12}{2} = 0.94[/tex], so [tex]Z = 1.555[/tex].

The lower limit of this interval is:

[tex]\pi - z\sqrt{\frac{\pi(1-\pi)}{n}} = 0.088 - 1.555\sqrt{\frac{0.088*0.912}{160}} = 0.053[/tex]

The upper limit of this interval is:

[tex]\pi + z\sqrt{\frac{\pi(1-\pi)}{n}} = 0.088 + 1.555\sqrt{\frac{0.088*0.912}{160}} = 0.123[/tex]

The 88% confidence interval for the proportion of defectives today is (0.053, 0.123)

Answer:

5.12 x 10¹¹ bit

Step-by-step explanation:

1GB = 8 x 10⁹ bits

so 64gb = 64 x 8 x 10⁹

= 512 x 10⁹

= 5.12 x 10¹¹ bits

scientific notation = 5.12 x 10¹¹ bits

standard Notation = 512 ,000,000,000 bits.

Answer:

2

Step-by-step explanation:

Since there are four negative signs, we have -1 multiplying each other 4 times,  multiplying by positive 2. This is then 1 * 2, which is 2.

Answer:

+2

Step-by-step explanation:

=> -(-(-(-2))))

=> -(-(+2))

=> -(-2)

=> +2

Answer:

B) 92.03 < μ < 97.97

99% confidence interval for the mean score of all students.

92.03 < μ < 97.97

Step-by-step explanation:

Step(i):-

Given sample mean (x⁻) = 95

standard deviation of the sample (s) = 6.6

Random sample size 'n' = 30

99% confidence interval for the mean score of all students.

[tex]((x^{-} - Z_{0.01} \frac{S}{\sqrt{n} } , (x^{-} + Z_{0.01} \frac{S}{\sqrt{n} })[/tex]

step(ii):-

Degrees of freedom

ν =   n-1 = 30-1 =29

[tex]t_{0.01} = 2.462[/tex]

99% confidence interval for the mean score of all students.

[tex]((95 - 2.462 \frac{6.6}{\sqrt{30} } , 95 + 2.462\frac{6.6}{\sqrt{30} } )[/tex]

( 95 - 2.966 , 95 + 2.966)

(92.03 , 97.97)

Final answer:-

99% confidence interval for the mean score of all students.

92.03 < μ < 97.97

Answer:

Length: 18

Width: 9

Step-by-step explanation:

Denote the width as x, hence the length is x+9. As a result, you can create the equation x(x+9) = 162. Solving, you find x = 9.

Answer:

[tex]t=\frac{10.8-11}{\frac{1.5}{\sqrt{9}}}=-0.4[/tex]    

The degrees of freedom are given by:

[tex]df=n-1=9-1=8[/tex]  

And the p value would be given by:

[tex]p_v =P(t_{(8)}<-0.4)=0.350[/tex]  

Since the p value is higher than the the significance level of 0.05 we have enough evidence to FAIL to reject the null hypothesis and we can conclude that the true mean is not significantly different from the traditional methods.

Step-by-step explanation:

Assuming this first part of the problem obtained from the web: "Using traditional methods, it takes 11.0 hours to receive a basic driving license. A new license training method using Computer Aided Instruction (CAI) has been proposed"

Information given

[tex]\bar X=10.8[/tex] represent the mean height for the sample  

[tex]s=1.5[/tex] represent the sample standard deviation

[tex]n=9[/tex] sample size  

[tex]\mu_o =11[/tex] represent the value that we want to test

[tex]\alpha=0.05[/tex] represent the significance level

t would represent the statistic  

[tex]p_v[/tex] represent the p value

Hypothesis to test

We want to check if the true mean for this case is equal to 11 or not, the system of hypothesis would be:  

Null hypothesis:[tex]\mu = 11[/tex]  

Alternative hypothesis:[tex]\mu \neq 11[/tex]  

The statistic would be given by:

[tex]t=\frac{\bar X-\mu_o}{\frac{s}{\sqrt{n}}}[/tex]  (1)  

Replacing the info given we got:

[tex]t=\frac{10.8-11}{\frac{1.5}{\sqrt{9}}}=-0.4[/tex]    

The degrees of freedom are given by:

[tex]df=n-1=9-1=8[/tex]  

And the p value would be given by:

[tex]p_v =P(t_{(8)}<-0.4)=0.350[/tex]  

Since the p value is higher than the the significance level of 0.05 we have enough evidence to FAIL to reject the null hypothesis and we can conclude that the true mean is not significantly different from the traditional methods.

Answer:

17x +7y

Step-by-step explanation:

8x + 10y + 9x - 3y

Combine like terms

8x+ 9x          + 10y - 3y

17x                   +7y

8x+9x are like terms    and 10y -3y are like terms

Answer:

17x + 7y

Step-by-step explanation:

8x + 10y + 9x - 3y

Rearrange.

8x + 9x + 10y - 3y

Factor out x and y.

x (8 + 9) + y (10 - 3)

Add or subtract.

x (17) + y (7)

17x + 7y

Step-by-step explanation:

1.07×1.25

=1.3375 euros

Answer:

[tex]\boxed{\sf \ \ \ 49a^8b^6c^2 \ \ \ }[/tex]

Step-by-step explanation:

Hello,

[tex](-7a^4b^3c)^2=(-1)^27^2a^{4*2}b^{3*2}c^2=49a^8b^6c^2[/tex]

as

[tex](-1)^2=1[/tex]

Answer:

A. The E(Y) is 0.80

B. The expected amount of the surcharges is $165

Step-by-step explanation:

A. In order to calculate the E(Y), we would have to calculate the following formula:

E(Y)=∑yp(y)

E(Y)=(0*0.5)+(1*0.25)+(2*0.20)+(3*0.05)

E(Y)=0+0.25+0.40+0.15

E(Y)=0.80

B. In order to calculate the expected amount of the surcharges we would have to calculate the following formula:

E($110Y∧2)=110E(Y∧2)

=110∑y∧2p(y)

=110((0∧2*0.5)+(1∧2*0.25)+(2∧2*0.20)+(3∧2*0.05))

110(0+0.25+0.80+0.45)

=$165

Question:

You are interested in estimating the the mean age of the citizens living in your community. In order to do this, you plan on constructing a confidence interval; however, you are not sure how many citizens should be included in the sample. If you want your sample estimate to be within 5 years of the actual mean with a confidence level of 97% , how many citizens should be included in your sample? Assume that the standard deviation of the ages of all the citizens in this community is 18 years.

Answer:

61.03

Step-by-step explanation:

Given:

Standard deviation = 18

Sample estimate = 5

Confidence level = 97%

Required:

Find sample size, n.

First find the Z value. Using zscore table

Z-value at a confidence level of 97% = 2.17

To find the sample size, use the formula below:

[tex] n = (Z * \frac{\sigma}{E})^2[/tex]

[tex] n = ( 2.17 * \frac{18}{5})^2 [/tex]

[tex] n = (2.17 * 3.6)^2 [/tex]

[tex] n = (7.812)^2 [/tex]

[tex] n = 61.03 [/tex]

Sample size = 61.03

Answer:

Luther is wrong

Wade is right

Step-by-step explanation:

Luther's case 2^3 = 2x2x2 = 8

Wade's case 3^3 = 3 x 3 = 9

Answer:

Luther is incorrect, while Wade is correct. (2)(2)(2)=8, not 9. (3)(3)= 9.

Step-by-step explanation:

I put that as my answer and it was counted as right.

Answer:

X is 3 units.

Step-by-step explanation:

Volume of prism is cross sectional area multiplied by length. So 1/2 ×2× x ×2 into 3x, which is equal to 6x^2. So, 6x^2=54. Therefore, x=3.

Answer:

[tex]z=\frac{404-409}{\frac{24}{\sqrt{42}}}=-1.35[/tex]  

The p value for this case is given by:

[tex]p_v =P(z<-1.35)=0.0885[/tex]  

For this case the p value is higher than the significance level given so we have enough evidence to FAIL to reject the null hypothesis and we can't conclude that the true mean is significantly less than 409

Step-by-step explanation:

Information given

[tex]\bar X=404[/tex] represent the sample mean

[tex]\sigma=24[/tex] represent the population standard deviation

[tex]n=42[/tex] sample size  

[tex]\mu_o =409[/tex] represent the value to verify

[tex]\alpha=0.01[/tex] represent the significance level for the hypothesis test.  

z would represent the statistic (variable of interest)  

[tex]p_v[/tex] represent the p value

Hypothesis to test

We want to verify if the true mean is less than 409, the system of hypothesis would be:  

Null hypothesis:[tex]\mu \geq 409[/tex]  

Alternative hypothesis:[tex]\mu < 409[/tex]  

The statistic for this case is given by:

[tex]z=\frac{\bar X-\mu_o}{\frac{\sigma}{\sqrt{n}}}[/tex] (1)  

Replacing the info we got:

[tex]z=\frac{404-409}{\frac{24}{\sqrt{42}}}=-1.35[/tex]  

The p value for this case is given by:

[tex]p_v =P(z<-1.35)=0.0885[/tex]  

For this case the p value is higher than the significance level given so we have enough evidence to FAIL to reject the null hypothesis and we can't conclude that the true mean is significantly less than 409

Answer:

  193.77 < p < 1806.23

Step-by-step explanation:

You want R(p) > 2,100,000, so ...

  -6p^2 +12000p > 2100000

  p^2 -2000p < -350000 . . . . divide by -6

Adding (2000/2)^2 = 1000000 will "complete the square".

  p^2 -2000p +1000000 < 650000 . . . . complete the square

  (p -1000)^2 < 650000

  -√650000 < p -1000 < √650000 . . . . take the square root

  1000 -806.23 < p < 1000 +806.23 . . . .add 1000

  193.77 < p < 1806.23 . . . . range of prices for desired revenue

Answer:

________________________

Answer:

Store A

Step-by-step explanation:

So. What we are going to want to do here is start off by having two stores obviously. And we have the sales that they have. If the discount is 20% rhat means the new price will be 80% of 250. So we take 250 x .8 = 200

If the discount is 25%, that means the new price will be 75% of what it was before hand. So we take 280 x .75 = 210. So the better price is at Store a

Answer:

(a) 125

[tex](b) \dfrac{1}{125}[/tex]

[tex](c) \dfrac{124}{125}[/tex]

Step-by-step explanation:

We are given that access code consists of 3 digits.

Each digit can be any digit through 1 to 5 and can be repeated.

Now, this problem is equivalent to the problem that we have to find:

The number of 3 digit numbers that can be formed using the digits 1 to 5 with repetition allowed.

(a) We have 3 places here, unit's, ten's and hundred's places respectively and  each of the 3 places have 5 possibilities (any digit allowed with repetition).

So, total number of access codes possible:

[tex]5\times 5 \times 5 = 125[/tex]

(b) Suppose, an access code is randomly selected, what is the probability that it will be correct.

Formula for probability of an event E can be observed as:

[tex]P(E) = \dfrac{\text{Number of favorable cases}}{\text {Total number of cases}}[/tex]

Here, only 1 code is correct, so

Number of favorable cases = 1

Total number of cases = 125

So, required probability:

[tex]P(E) = \dfrac{1}{125}[/tex]

(c) Probability of not selecting the correct access code on first time:

[tex]P(\overline E) = 1-P(E)\\\Rightarrow P(\overline E) = 1-\dfrac{1}{125}\\\Rightarrow P(\overline E) = \dfrac{125-1}{125}\\\Rightarrow P(\overline E) = \dfrac{124}{125}[/tex]

So, the answers are:

(a) 125

[tex](b) \dfrac{1}{125}[/tex]

[tex](c) \dfrac{124}{125}[/tex]

Answer:

Option C (-4,-1) (In Quadrant III)

Step-by-step explanation:

Coordinate = (-4,1)

=> Reflecting over y-axis will make the coordinate (4,1)

=> Reflecting across x-axis will make the coordinate (4,-1)

=> Rotating 180 will make it (-4,-1)

Answer:8.2 x 10^5

Step-by-step explanation:

Answer:

The amount of money separating the lowest 80% of the amount invested from the highest 20% in a sampling distribution of 10 of the family's real estate holdings is $238,281.57.

Step-by-step explanation:

Let the random variable X represent the amount of money that the family has invested in different real estate properties.

The random variable X follows a Normal distribution with parameters μ = $225,000 and σ = $50,000.

It is provided that the family has invested in n = 10 different real estate properties.

Then the mean and standard deviation of amount of money that the family has invested in these 10 different real estate properties is:

[tex]\mu_{\bar x}=\mu=\$225,000\\\\\sigma_{\bar x}=\frac{\sigma}{\sqrt{n}}=\frac{50000}{\sqrt{10}}=15811.39[/tex]

Now the lowest 80% of the amount invested can be represented as follows:

[tex]P(\bar X<\bar x)=0.80\\\\\Rightarrow P(Z<z)=0.80[/tex]

The value of z is 0.84.

*Use a z-table.

Compute the value of the mean amount invested as follows:

[tex]\bar x=\mu_{\bar x}+z\cdot \sigma_{\bar x}[/tex]

   [tex]=225000+(0.84\times 15811.39)\\\\=225000+13281.5676\\\\=238281.5676\\\\\approx 238281.57[/tex]

Thus, the amount of money separating the lowest 80% of the amount invested from the highest 20% in a sampling distribution of 10 of the family's real estate holdings is $238,281.57.

Answer:

[tex] \frac{1}{2} [/tex]

Step-by-step explanation:

[tex]scale \: factor = \frac{5}{10} = \frac{1}{2} \\ [/tex]

Answer:

The answer is "[tex]\bold{\frac{32}{3}}\\[/tex]"

Step-by-step explanation:

The rectangle should also be symmetrical to it because of the symmetry to the y-axis  The pole of the y-axis.  Its lower two vertices are (-x,0). it means that  

and (-x,0), and (x,0). Therefore the base measurement of the rectangle is 2x. The top vertices on the parabola are as follows:  

The calculation of the height of the rectangle also is clearly 16-x^2, (-x,16,-x^2) and (x,16,-x^2).  

The area of the rectangle:

[tex]A(x)=(2x)(16-x^2)\\\\A(x)=32x-2x^3[/tex]

The local extremes of this function are where the first derivative is 0:

[tex]A'(x)=32-6x^2\\\\32-6x^2=0\\\\x= \pm\sqrt{\frac{32}{6}}\\\\x= \pm\frac{4\sqrt{3}}{3}\\\\[/tex]

Simply ignore the negative root because we need a positive length calculation

It wants a maximum, this we want to see if the second derivative's profit at the end is negative.

[tex]A''\frac{4\sqrt{3}}{3} = -12\frac{4\sqrt{3}}{3}<0\\\\2.\frac{4\sqrt{3}}{3}= \frac{8\sqrt{3}}{3}\\\\\vertical \ dimension\\\\16-(\frac{4\sqrt{3}}{3})^2= \frac{32}{3}[/tex]

Answer:

[tex]-\frac{161}{9}=\\or\\-16\frac{8}{9}[/tex]

Step-by-step explanation:

[tex]-6\frac{4}{9}-3\frac{2}{9}-8\frac{2}{9}=\\\\-\frac{58}{9}-\frac{29}{9}-\frac{74}{9}=\\\\-\frac{161}{9}=\\\\-16\frac{8}{9}[/tex]