A study was conducted in order to estimate ?, the mean number of weekly hours that U.S. adults use computers at home. Suppose a random sample of 81 U.S. adults gives a mean weekly computer usage time of 8.5 hours and that from prior studies, the population standard deviation is assumed to be ? = 3.6 hours.
A similar study conducted a year earlier estimated that ?, the mean number of weekly hours that U.S. adults use computers at home, was 8 hours. We would like to test (at the usual significance level of 5%) whether the current study provides significant evidence that this mean has changed since the previous year.
Using a 95% confidence interval of (7.7, 9.3), our conclusion is that:
a. the current study does provide significant evidence that the mean number of weekly hours has changed over the past year, since 8 falls outside the confidence interval.
b. the current study does not provide significant evidence that the mean number of weekly hours has changed over the past year, since 8 falls outside the confidence interval.
c. the current study does provide significant evidence that the mean number of weekly hours has changed over the past year, since 8 falls inside the confidence interval.
d. the current study does not provide significant evidence that the mean number of weekly hours has changed over the past year, since 8 falls inside the confidence interval.
e. None of the above. The only way to reach a conclusion is by finding the p-value of the test.

Answer:

30.03

Step-by-step explanation:

[(33.7)² - (15.3)²]^½

= [1135.69 - 234.09]^½

= [901.6]^½

= 30.02665483

= 30.03 (4sf)

Answer:

a = 9

Step-by-step explanation:

The given trinomial is :

[tex]x^2-6x+\_\_\__[/tex]

let the blank is a.

So, we need to find the value of a so that it results in a perfect square trinomial.

We know that, [tex](m-n)^2=m^2-2mn+n^2[/tex]

So,

[tex]x^2-6x+a=x^2-2(1)(3)+3^2\\=(x-3)^2[/tex]

So, the value of a is 9. If a is 9, then only it would be a perfect square trinomial.

Answer:

4×10⁶ is the answer.........

Answer:

[tex]4 \times {10}^{6} [/tex]

Step-by-step explanation:

[tex] \frac{8 \times {10}^{24} }{2 \times {10}^{18} } [/tex]

[tex] \frac{4 \times {10}^{24} }{ {10}^{18} } [/tex]

[tex] = 4 \times {10}^{6} [/tex]

Answer:

196

Step-by-step explanation:

We will use the formula:

Surface Area of A / Surface area of B = (Height of A /Height of B)^2

49/S2 = (4/8)^2

49/S2 = 1/4

S2 = 196

Answred by Gauthmath

Answer:

The 95% confidence interval for the true difference between the mean times on this course for teams of Siberian Huskies and teams of other breeds of sled dogs is (-0.8276, 0.2276).

Step-by-step explanation:

Before building the confidence interval, we need to understand the central limit theorem and subtraction of normal variables.

Central Limit Theorem

The Central Limit Theorem establishes that, for a normally distributed random variable X, with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean [tex]\mu[/tex] and standard deviation [tex]s = \frac{\sigma}{\sqrt{n}}[/tex].

For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.  

Subtraction between normal variables:

When two normal variables are subtracted, the mean is the difference of the means, while the standard deviation is the square root of the sum of the variances.

Siberian Huskies:

Sample of 47, mean of 5.2 minutes, standard deviation of 1.4. So

[tex]\mu_1 = 5.2[/tex]

[tex]s_1 = \frac{1.4}{\sqrt{47}} = 0.2042[/tex]

Others:

Sample of 39, mean of 5.5 minutes, standard deviation of 1.1. So

[tex]\mu_2 = 5.5[/tex]

[tex]s_2 = \frac{1.1}{\sqrt{39}} = 0.1761[/tex]

Distribution of the difference:

[tex]\mu = \mu_1 - \mu_2 = 5.2 - 5.5 = -0.3[/tex]

[tex]s = \sqrt{s_1^2+s_2^2} = \sqrt{0.2042^2+0.1761^2} = 0.2692[/tex]

Confidence interval:

We have that to find our [tex]\alpha[/tex] level, that is the subtraction of 1 by the confidence interval divided by 2. So:

[tex]\alpha = \frac{1 - 0.95}{2} = 0.025[/tex]

Now, we have to find z in the Z-table as such z has a p-value of [tex]1 - \alpha[/tex].

That is z with a pvalue of [tex]1 - 0.025 = 0.975[/tex], so Z = 1.96.

Now, find the margin of error M as such

[tex]M = zs[/tex]

In which s is the standard error. So

[tex]M = 1.96(0.2692) = 0.5276[/tex]

The lower end of the interval is the sample mean subtracted by M. So it is -0.3 - 0.5276 = -0.8276.

The upper end of the interval is the sample mean added to M. So it is -0.3 + 0.5276 = 0.2276

The 95% confidence interval for the true difference between the mean times on this course for teams of Siberian Huskies and teams of other breeds of sled dogs is (-0.8276, 0.2276).

Answer:

3/4y +5/3 = x

Step-by-step explanation:

y = 4(3x-5)/9

Multiply each side by 9

9y = 4(3x-5)/9*9

9y = 4(3x-5)

Divide each side by 4

9/4 y = 4/4 (3x-5)

9/4y = 3x-5

Add 5 to each side

9/4y +5 = 3x-5+5

9/4y +5 = 3x

Divide by 3

9/4 y *1/3 +5/3 = 3x/3

3/4y +5/3 = x

Answer:

...

Step-by-step explanation:

seeee the above picture

the answer is 1/12

the first rolling a 4 has a 1/6 chance of happening and half of the numbers on the die are odd, so 1/6*1/2=1/12

Answer:

x=27

Step-by-step explanation:

The sum of the angles of a triangle are 180 degrees

90 + x+15 + 2x-6 = 180

Combine like terms

3x+99=180

Subtract 99 from each side

3x+99-99=180-99

3x =81

Divide each side by 3

3x/3 = 81/3

x=27

Answer:

Male & action movie among a group of total 479

Step-by-step explanation:

We only choose male from action movie category so:

p = 105/ 479 = 0.22

The probability that a randomly chosen person from this group is male and attended an action movie will be 0.22. Then the correct option is C.

Its basic premise is that something will almost certainly happen. The percentage of favorable events to the total number of occurrences.

This table shows how many male and female students attended two different movies.

                   Action      Drama          Total

Mala             105            124              229

Female         99             151               250

Total            204           275              479

Then the probability that a randomly chosen person from this group is male and attended an action movie will be

Favorable event = 105

Total event = 479

Then the probability will be

P = 105 / 479

P = 0.219

P ≈ 0.22

Then the correct option is C.

More about the probability link is given below.

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Answer:

The sum of 1/6 and 1/7 would be 13/42, or, if you wanted the answer in decimal form rounded to the nearest hundredth, it would be about 0.31.

To find the sum of 1/6 and 1/7, we cannot simply add the numerators together and maintain the same denominator. This is because 1/6 and 1/7 have different denominators, so we don't know which denominator to maintain!

To fix this we need to find a number that is divisible by both 6 and 7. One easy way to do this is to multiply the two numbers together:

6 x 7 = 42

If we were to change the denominator to 42 for each fraction, we could add the numerators together and maintain a denominator of 42. However, this means we must change the numerator of each fraction along with its denominator.

Let's start with 1/6. We can multiply 6 by 7 to obtain 42, but this means we also have to multiply 1 by 7 to keep the fraction proportionate. If the fraction does not maintain the same proportion, it will be a completely different fraction!

We know that 1 x 7 = 7, so it is safe to say that 1/6 is equal to 7/42.

We can apply the same logic to 1/7. Since 7 x 6 is 42 we need to multiply 1 by 6 along with 7. Note: you cannot multiply each number by 7 this time, because 7 x 7 would be 49, not 42. In multiplying the numerator and denominator by 6 we know that 1/7 = 6/42.

Now we have an equation of:

6/42 + 7/42

Now we can add it as we would normally by adding the numerators and keeping the denominator to get:

6/42 + 7/42 = 13/42

If you needed the answer in decimal form it would be about 0.3095238095, or 0.31 rounded to the nearest hundredth.

I hope this helped.

Answer:

14

Step-by-step explanation:

The angles created by the diagonals of a rhombus add up to 360 meaning each one is 90 degrees

5x+20 = 90

subtract 20 from both sides

5x = 70

divide by 5 on both sides

x=14

Answer:

54% ...

Step-by-step explanation:

this is the answer I guess

The confidence level that produces the widest interval is the one with the highest percentage, which is 54%.

Option B is the correct answer.

A z-score also called a standard score is a measure of how many standard deviations a data point is away from the given mean of a distribution.

It measures the unusual or extreme a particular data point is compared to the rest of the distribution

We have,

The width of a confidence interval is proportional to the critical value of the corresponding confidence level.

The critical value is determined by the standard normal distribution or t-distribution, depending on the sample size and whether the population standard deviation is known.

In general,

The wider the confidence interval, the less precise the estimate of the population means.

Therefore, we want to choose the confidence level that produces the widest interval, which corresponds to the largest critical value.

For a given sample size,

The critical value increases as the confidence level increases.

For example, the critical value for a 95% confidence level is larger than the critical value for a 90% confidence level.

Therefore,

The confidence level that produces the widest interval is the one with the highest percentage, which is 54%.

Learn more about z-score here:

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87 is the mean.

To find the mean, you must

- add all of the numbers

- divide by the amount of numbers given

In this case, you would want to do (86 + 80 + 95)/3. This would give you an answer of 87.

Answer:

The number is 448.

Step-by-step explanation:

Hope it helps

Answer:

x = 34

Step-by-step explanation:

Pytago:

x[tex]30^{2} + 16^{2} = x^2\\x = \sqrt{30^2 + 16^2} \\x = 34[/tex]

Answer:

The answer is (C)

17.37 + .50x

ED2021

Answer:

700,000

Step-by-step explanation:

700,000 is already a 100,000, therefore there is no rounding to do.

Answer:

700,000 is the answer

Step-by-step explanation:

Answer:  [tex]\frac{3}{2}[/tex]

Step-by-step explanation:

First, we need to open the brackets on either side of the equation.

[tex]\frac{z}3}[/tex] - 4z+4 = 5z-10+1

After opening the brackets, we need to separate the variables from the constants.

[tex]\frac{z}{3}[/tex] -4z-5z = -10+1-4

Then we need to convert the variable fraction into a normal variable by multiplying the variable fraction and also all other terms in the equation.

3([tex]\frac{z}{3}[/tex]) 3(-4z) 3(-5z) = 3(-10) + 3(1) + 3(-4)

z -12z -15z = -30+3-12

Now, we can simplify the equation !

-26z = -39

z = -39÷-26

  =  [tex]\frac{3}{2}[/tex]

Answer:

63°

Step-by-step explanation:

9514 1404 393

Answer:

  9

Step-by-step explanation:

If x is the number of 10-inch stones, then (x-1) is the number of 5-inch stones, and the total width is ...

  10x +5(x-1) = 130

  15x -5 = 130 . . . . . . . eliminate parentheses

  15x = 135 . . . . . . add 5

  x = 9 . . . . . . . divide by 15

Wesley will need 9 10-inch stones for one row.

Answer:

Pencils = 325 ; Pens = 975 ; Markers = 650

Step-by-step explanation:

Let :

Number of Pencils = x

Number of pens = y

Number of markers = z

2 times as many markers as pencils

z = 2x

3 times as many pens as pencils

y = 3x

x + y + z = 1950

Write z and y in terms of x in the equation :

x + 3x + 2x = 1950

6x = 1950

Divide both sides by 6

6x / 6 = 1950 / 6

x = 325

Number of pencils = 325

Pens = 3 * 325 = 975

Markers = 2 * 325 = 650

Pencils = 325 ; Pens = 975 ; Markers = 650

======================================================

Explanation:

The five number summary is the set of these items, in this exact order

So with the five number summary 4.6, 14.3, 19.7, 26.1, 31.2, we see that

Q1 = 14.3 and Q3 = 26.1

Subtracting these two values gets us the IQR (interquartile range)

IQR = Q3 - Q1

IQR = 26.1 - 14.3

IQR = 11.8

Answer:

The appropriate answer is "523".

Step-by-step explanation:

Given:

Margin of error,

E = 0.04

Confidence level,

= 95%

Educated guess,

[tex]P_g[/tex] = 0.32

According to the question,

[tex]\alpha = \frac{100-95}{100}[/tex]

   [tex]=0.05[/tex]

[tex]\frac{\alpha}{2} = \frac{0.05}{2}[/tex]

   [tex]=0.025[/tex]

[tex]Z_{0.025} = 1.96[/tex]

The sample size will be:

⇒ [tex]n=P_g (1-P_g) (\frac{Z_{\frac{\alpha}{2} }}{E} )^2[/tex]

By substituting the values, we get

       [tex]=0.32(1-0.32)(\frac{1.96}{0.04} )^2[/tex]

       [tex]=0.32\times 0.68\times (49)^2[/tex]

       [tex]=0.32\times 0.68\times 2401[/tex]

       [tex]=522.4576[/tex]

or,

       [tex]=523[/tex]

Answer:

a) The 99% confidence interval for the difference of proportions is (0.0844, 0.3012).

b) We are 99% sure that the true difference in proportions is between 0.0844 and 0.3012. Since all values are positive, there is significant evidence at the 1 - 0.99 = 0.01 significance level to conclude that the proportion is the Fort Defiance region is higher than in the Indian Wells region.

Step-by-step explanation:

Before finding the confidence interval, we need to understand the central limit theorem and subtraction of normal variables.

Central Limit Theorem

The Central Limit Theorem establishes that, for a normally distributed random variable X, with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean [tex]\mu[/tex] and standard deviation [tex]s = \frac{\sigma}{\sqrt{n}}[/tex].

For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.

For a proportion p in a sample of size n, the sampling distribution of the sample proportion will be approximately normal with mean [tex]\mu = p[/tex] and standard deviation [tex]s = \sqrt{\frac{p(1-p)}{n}}[/tex]

Subtraction between normal variables:

When two normal variables are subtracted, the mean is the difference of the means, while the standard deviation is the square root of the sum of the variances.

Fort Defiance:

69 out of 210, so:

[tex]p_1 = \frac{69}{210} = 0.3286[/tex]

[tex]s_1 = \sqrt{\frac{0.3286*0.6714}{210}} = 0.0324[/tex]

Indian Wells:

22 out of 162, so:

[tex]p_2 = \frac{22}{162} = 0.1358[/tex]

[tex]s_2 = \sqrt{\frac{0.1358*0.8642}{162}} = 0.0269[/tex]

Distribution of the difference:

[tex]p = p_1 - p_2 = 0.3286 - 0.1358 = 0.1928[/tex]

[tex]s = \sqrt{s_1^2+s_2^2} = \sqrt{0.0324^2 + 0.0269^2} = 0.0421[/tex]

a. Find a 99% confidence interval for p1 -p2.

The confidence interval is:

[tex]p \pm zs[/tex]

In which

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

99% confidence level

So [tex]\alpha = 0.01[/tex], z is the value of Z that has a p-value of [tex]1 - \frac{0.01}{2} = 0.995[/tex], so [tex]Z = 2.575[/tex].

The lower bound of the interval is:

[tex]p - zs = 0.1928 - 2.575*0.0421 = 0.0844[/tex]

The upper bound of the interval is:

[tex]p + zs = 0.1928 + 2.575*0.0421 = 0.3012[/tex]

The 99% confidence interval for the difference of proportions is (0.0844, 0.3012).

Question b:

We are 99% sure that the true difference in proportions is between 0.0844 and 0.3012. Since all values are positive, there is significant evidence at the 1 - 0.99 = 0.01 significance level to conclude that the proportion is the Fort Defiance region is higher than in the Indian Wells region.

Answer:

all answer are in given solution

Answer:

-0.316227766

Step-by-step explanation:

0.316227766

Step-by-step explanation:

Which correlation coefficient indicates the data set with the strongest linear correlation?

0.66

The correlation coefficient indicates the data set with the strongest linear correlation is -0.83

"It measures the strength of the relationship between two relative variables."

"When the rate of change is constant between two variables then it is said to be linear correlation."

For given example,

We have been given correlation coefficients.

We need to find the correlation coefficient that indicates the data set with the strongest linear correlation.

We know, the correlation coefficient lies between -1 to 1.

So, the strongest linear correlation is indicated by a correlation coefficient of -1 or 1.

From given correlation coefficients,

-0.83 is close to -1.

Therefore, the correlation coefficient indicates the data set with the strongest linear correlation is -0.83

Learn more about linear correlation coefficient here:

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Answer:

x=20.938

Step-by-step explanation:

-2.053748911 = (x - 21)/.03

x=20.938