A civil engineer is analyzing the compressive strength of concrete. Compressive strength is normally distributed with A random sample of 12 sample specimens has a mean compressive strength of psi. Round your answers to 1 decimal place. (a) Calculate the 95% two-sided confidence interval on the true mean compressive strength of concrete. Enter your answer; 95% confidence interval, lower bound Enter your answer; 95% confidence interval, upper bound (b) Calculate the 99% two-sided confidence interval on the true mean compressive strength of concrete.

Answers

Answer 1

Answer:

95%: (3278.354 ; 3270.083)

99% : (3221.646 ; 3278.354)

Step-by-step explanation:

Given :

Sample size, n = 12

Mean, xbar = 3250

Sample standard deviation = √1000

The 95% confidence interval :

Mean ± Margin of error

Margin of Error = Tcritical * s/√n

Tcritical at 0.05, df=12-1 = 11 ;

Tcritical at 95% = 2.20

Hence,

Margin of Error = (2.20 * √1000/√12) = 20.083

Confidence interval : 3250 ± 20.083

Lower boundary = 3250 - 20.083 = 3229.917

Upper boundary = 3250 + 20.083 = 3270.083

2.)

The 99% confidence interval :

Mean ± Margin of error

Margin of Error = Tcritical * s/√n

Tcritical at 0.01, df=12-1 = 11 ;

Tcritical at 99% = 3.106

Hence,

Margin of Error = (3.106 * √1000/√12) = 28.354

Confidence interval : 3250 ± 28.354

Lower boundary = 3250 - 28.354 = 3221.646

Upper boundary = 3250 + 28.354 = 3278.354


Related Questions

You paid $6.99 for a shirt that was 70% of what was the original price of the shirt? ​

Answers

Answer:

$23.3

Step-by-step explanation:

you can use ratios to solve this:

$6.99/x=0.30/0.100 then cross multiply to get 0.3x=6.99

So, 6.99 divided by 0.3 = 23.3

so the original price is $23.3

Need help with this one please

Answers

it right answer is Clovis 2.5% it answer

Sarah ordered 39 shirts that cost $8 each. She can sell each shirt for $16.19. She sold 32 shirts to customers. She had to return 7 shirts and pay a $1.4 charge for each returned shirt. Find Sarah's profit.

Answers

Answer:

$196.28

Step-by-step explanation:

Original cost: 39 × $8 = $312

Revenue: 32 × $16.19 = $518.08

Return charge: 7 × $1.4 = $9.8

$312 + $9.8 = total cost, which is $321.8

$518.08 - $321.8 = profit

Profit = $196.28

the complement of guessing 5 correct answers on a 5 question true or false examination is ​
​​​

Answers

Answer:

Guessing at least one incorrect answer

Step-by-step explanation:

The complement of guessing 5 correct answers on a 5-question true/false exam is-

Guessing at least one incorrect answer because, when 1 or more questions are incorrectly guessed, the event of 5 correct answers can not occur.

the diagram shows a regular dodecagon. a) work out the size of one interior angle. b) work out the size of one exterior angle.

Answers

Answer: Interior angle: 150 degrees Exterior angle: 30 degrees

Step-by-step explanation:

We use the angle formula to find the value of an interior angle: 180*(12-2)/12 = 150 degrees. Since an exterior angle is the supplement of an interior angle, the measure of an exterior angle is 180 - 150 = 30 degrees

Use the coordinates of the labeled point to find a point-slope equation of the
line.
5
5
(-2,-5) 6.5
>
O A. y- 5 = -2(x - 2)
O B. y + 5 = 2(x + 2)
O C. y + 5 = -2(x + 2)
OD. y- 5 = 2(x - 2)

Answers

Answer:

B. [tex] y + 5 = 2(x + 2) [/tex]

Step-by-step explanation:

Point-slope equation is given as [tex] y - b = m(x - a) [/tex], where,

(a, b) = (-2, -5)

[tex] m = slope = \frac{y_2 - y_1}{x_2 - x_1} [/tex]

Using two points on the line (-2, -5) and (0, -1),

Slope (m) = (-1 -(-5))/(0 -(-2)) = 4/2

m = 2

✔️To write the equation in point-slope form, substitute a = -2, b = -5, and m = 2 into [tex] y - b = m(x - a) [/tex]

Thus:

[tex] y - (-5) = 2(x - (-2)) [/tex]

[tex] y + 5 = 2(x + 2) [/tex]

g A. (Points: 7) Compute (without using a calculator) 241^257 mod 12 B. (Points: 3) Compute Z*20 C. (Points: 6) Find the multiplicative inverse of 7 in Z19

Answers

Answer:

[tex]241^{257}\ mod\ 12 =1[/tex]

[tex]7 * 20 = 140[/tex]

[tex]\frac{1}{700}[/tex]

Step-by-step explanation:

Solving (a): 241^257 mod 12

To do this, we simply calculate [tex]241\ mod\ 12[/tex]

Because [tex]a\ mod\ b = a^n\ mod\ b[/tex]

The highest number less than or equal to 241 that is divisible by 12 is 240; So:

[tex]241\ mod\ 12 = 241- 240[/tex]

[tex]241\ mod\ 12 =1[/tex]

Hence:

[tex]241^{257}\ mod\ 12 =1[/tex]

Solving (b): 7 * 20

[tex]7 * 20 = 140[/tex]

Solving (c): Multiplicative inverse of 7 in 719

The position of 7 in 719 is 700

So, the required inverse is 1/700 ---- i.e. we simply divide 1 by the number

Will give brainliest answer

Answers

Answer:

1. log3 81 = 4

2. 4 3/2=8

Step-by-step explanation:

1. Convert the exponential equation to a logarithmic equation using the logarithm base (3)(3) of the right side (81)(81) equals the exponent (4)(4).

log3(81)=4

or

you can remember this

loga Y= X

so, a^x =y

2. Use the definition of a logarithm,

log

b

(

x

)

=

y

b

y

=

x

, to convert from the logarithmic form to the exponential form.

8. Calculate the Perimeter AND Area of
the RIGHT Triangle below.
17 m
10 m
21 m

Answers

Answer:

[tex]\text{Perimeter: }48\:\mathrm{m},\\\text{Area: }84\:\mathrm{m^2}[/tex]

Step-by-step explanation:

The area of a triangle with side lengths [tex]a[/tex], [tex]b[/tex], and [tex]c[/tex] is given by:

[tex]A=\sqrt{s(s-a)(s-b)(s-c)}[/tex], where [tex]s=\frac{a+b+c}{2}[/tex]

Substituting [tex]a=21, b=17, c=10[/tex], we have:

[tex]A=\sqrt{24(24-21)(24-17)(24-10)},\\A=\sqrt{24(3)(7)(14)},\\A=\sqrt{7,084},\\A=\boxed{84\:\mathrm{m^2}}[/tex]

The perimeter of a polygon is given by the sum of its sides. Since the triangle has sides 10, 17, and 21, its perimeter is [tex]10+17+21=\boxed{48\:\mathrm{m}}[/tex].

Uma pizzaria oferece em seu cardápio 12 sabores de pizza. Se um cliente pretende pedir 3 pizzas, então o número de maneiras que ele pode realizar esse pedido é;
•364
•220
•440
•1320

Answers

Answer:

Step-by-step explanation:

Partindo do pressuposto de que você pode ter coberturas duplas e triplas do mesmo item, o cálculo é relativamente simples. Para calcular as combinações possíveis; deve-se multiplicar as coberturas disponíveis pelo número total de coberturas permitidas. Este cálculo é semelhante a como olhamos para diferentes sistemas de contagem de base. Normalmente contamos com decimais (base 10), portanto, o número de combinações, se usar 3 dígitos, seria calculado por 10 x 10 x 10.

10x10 = 100

100x10 = 1000 combinações (0 a 999)

Sua pergunta sobre coberturas de pizza é a mesma, mas assumindo um sistema de numeração de base 12, então 12x12x12 ou 12³

Portanto, 1.728 combinações incluindo 0 (sem coberturas?) E também incluindo 12 ocasiões em que todas as 3 coberturas seriam iguais. Se esses cenários de pessoas forem restritos de modo que você só possa ter coberturas duplas máximas, etc., então essas combinações devem ser removidas (subtraídas do total de combinações permitidas).

Espero ter ajudado você a entender os princípios, então você deve ser capaz de trabalhar a partir disso, de muitas outras soluções semelhantes

The 2010 GSS provides the following statistics for the average years of education for lower-, working-, middle-, and upper-class respondents and their associated standard deviations. Assume that years of education are normally distributed in the population. Mean Standard Deviation N Lower-class 11.61 2.67 123 Working-class 12.80 2.85 697 Middle-class 14.45 3.08 626 Upper-class 15.45 2.98 38 How many years of education correspond to a Z score of +1.2 for upper-class respondents?

Answers

Answer:

The answer is "18.087 years".

Step-by-step explanation:

For upper class:

[tex]\mu=15.45 \ years\\\\\alpha=2.98 \ years\\\\[/tex]

[tex]P(Z \leq 1.2)[/tex] from the standard normal distribution on the table:

[tex]P(Z \leq 1.2) =0.8849\\\\x=z_{\alpha}+\mu\\\\[/tex]

  [tex]=0.8849 \times 2.98 +15.45\\\\ = 2.637002+15.45 \\\\=18.087 \ \ years\\[/tex]

Factor 2x2+25x+50. Rewrite the trinomial with the x-term expanded, using the two factors.

Answers

9514 1404 393

Answer:

rewrite: 2x^2 +5x +20x +50factored: (x +10)(2x +5)

Step-by-step explanation:

I find this approach the most straightforward of the various ways that trinomial factoring is explained or diagramed.

You want two factors of "ac" that have a total of "b". Here, that means you want factors of 2·50 = 100 that have a total of 25. It is helpful to know your times tables.

  100 = 1·100 = 2·50 = 4·25 = 5·20 = 10·10

The sums of these factor pairs are 101, 52, 29, 25, and 20. We want the pair with a sum of 25, so that's 5 and 20.

The trinomial can be rewritten using these factors as ...

  2x^2 +5x +20x +50

Then it can be factored by grouping consecutive pairs:

  (2x^2 +5x) +(20x +50) = x(2x +5) +10(2x +5) = (x +10)(2x +5)

_____

Additional comment

It doesn't matter which of the factors of the pair you write first. If our rewrite were ...

  2x^2 +20x +5x +50

Then the grouping and factoring would be (2x^2 +20x) +(5x +50)

  = 2x(x +10) +5(x +10) = (2x +5)(x +10) . . . . . same factoring

How do I find the missing number?

Answers

Answer:

to find the missing number is all u have to do is understand the problem and silve the problem!

Step-by-step explanation:

paki brainly po

Please guys help to solve this problem​

Answers

9514 1404 393

Answer:

  300

Step-by-step explanation:

Since nobody failed, the number who passed one or the other was 100%.

  P(O + W) = P(O) +P(W) -P(O&W)

  100% = 80% +70% -P(O&W)

  P(O&W) = 50% = 150 students

If 150 students are 50% of the examinees, then 100% will be 300 students.

Answer:

[tex]300[/tex]

hope it helps

#CARRYONLEARNING

Write 0.851 as a fraction in simplest form.

Answers

Answer:

[tex]\frac{851}{1000}[/tex]

Step-by-step explanation:

First, we can simply multiply that number by 1000, and divide again by 1000 to get a base fraction:

[tex].851\\\\= \frac{1000}{1000} \times .851\\\\= \frac{1000 \times .851}{1000}\\\\= \frac{851}{1000}[/tex]

851 is a secondary prime, having only two factors, both of which are prime.  Those factors are 23 and 37, neither of which is a factor of 1000, so this is already in simplest form.

A party supply company makes cone shaped party hats for children using thin cardboard. To the nearest square centimeter, how much cardboard is required to make the party hate use pie = 3.14.

Answers

Answer:

A. 754 cm²

Step-by-step explanation:

Amount of cardboard needed = surface area of the cone

Curved surface area of the cone = πrl

Where,

π = 3.14

r = ½(20) = 10 cm

l = 24 cm

Plug in the values into the formula

Curved surface area = 3.14 × 10 × 24 = 753.6 ≈ 754 cm²

g At a certain gas station, 30% of all customers use the restroom. What is the probability that, out of the next 10 customers, (a) exactly 4 will use the restroom

Answers

Answer:

[tex]P(x=4) = 0.200[/tex]

Step-by-step explanation:

Given

[tex]n=10[/tex] --- selected customers

[tex]x = 4[/tex] --- those that are expected to use the restroom

[tex]p =30\% = 0.30[/tex] --- proportion that uses the restroom

Required

[tex]P(x = 4)[/tex]

The question illustrates binomial probability and the formula is:

[tex]P(x) = ^nC_x * p^x * (1 - p)^{n - x}[/tex]

So, we have:

[tex]P(x=4) = ^{10}C_4 * (0.30)^4 * (1 - 0.30)^{10 - 4}[/tex]

[tex]P(x=4) = ^{10}C_4 * (0.30)^4 * (0.70)^6[/tex]

[tex]P(x=4) = 210* (0.30)^4 * (0.70)^6[/tex]

[tex]P(x=4) = 0.200[/tex]

Prove this plzzz help me​

Answers

Answer:

Answer is in the picture. have a look

it's tooooo easy who wants brain list​

Answers

Answer:

1) Isosceles

2) Acute

3) Right angled

4( Obtuse

5) Equilateral

1)isoceles
2)Acute
3) right angled
4)obtuse
5)Equilateral

What is the slope of the line?

Answers

5/5 using rise over run

How to solve and what is the answer

Answers

Answer:

5

Step-by-step explanation:

Help please!!!!!!!!!!!

Answers

Answer:

y = 14

Step-by-step explanation:

[tex] \frac{15}{21} = \frac{5}{7} [/tex]

[tex] \frac{10}{x} = \frac{5}{7} [/tex]

[tex]x = 14[/tex]

Now,

10/15 = y/21

15y = 10*21

y = 210/15

y = 14

This is a Right answer...

I hope you understand..

Mark me as brainliest...

Test the claim that the mean GPA of night students is larger than the mean GPA of day students at the 0.10 significance level. The null and alternative hypothesis would be: H 0 : p N ≥ p D H 1 : p N < p D H 0 : p N ≤ p D H 1 : p N > p D H 0 : p N = p D H 1 : p N ≠ p D H 0 : μ N ≤ μ D H 1 : μ N > μ D H 0 : μ N ≥ μ D H 1 : μ N < μ D H 0 : μ N = μ D H 1 : μ N ≠ μ D The test is: two-tailed right-tailed left-tailed The sample consisted of 30 night students, with a sample mean GPA of 3.34 and a standard deviation of 0.02, and 30 day students, with a sample mean GPA of 3.32 and a standard deviation of 0.08. The test statistic is: (to 2 decimals) Use the conservative degree of freedoms. The p-value is: (to 2 decimals) Based on this we: Reject the null hypothesis Fail to reject the null hypothesis

Answers

Answer:

H0 : μN ≤ μD

H1 : μN > μD

Right tailed

Test statistic = 1.33

Pvalue = 0.097

Fail to reject the Null

Step-by-step explanation:

H0 : μN ≤ μD

H1 : μN > μD

The test is right tailed ; culled from the direction of the greater than sign ">"

Night students :

n1 =30 x1= 3.34 s1 = 0.02

Day students:

n2 = 30 x2 = 3.32 s2 = 0.08

The test statistic :

(x1 - x2) / √(s1²/n1) + (s2²/n2)

T= (3.34 - 3.32) / √(0.02²/30) + (0.08²/30)

T = 0.02 / 0.0150554

Test statistic = 1.328

Using the conservative approach ;

df = Smaller of n1 - 1 or n2 - 1

df = 30 - 1 = 29

Pvalue(1.328, 29) = 0.097

At α = 0.10

Pvalue < α ; Hence, we reject H0 ; and conclude that there is significant evidence that GPA of night student is greater than GPA of day student

A certain list of movies were chosen from lists of recent Academy Award Best Picture winners, highest grossing movies, series movies (e.g. the Harry Potter series, the Spiderman series), and from the Sundance Film Festival and are being analyzed. The mean box office gross was $138.64 million with a standard deviation of $11.2526 million. Given this information, 98.49% of movies grossed greater than how much money (in millions)

Answers

what is the question?

At the 6th grade school dance, there are 132 boys, 89 girls, and 14 adults. What is the ratio of adults to boys at the school dance?​

Answers

Answer:

14 to 132

Step-by-step explanation:

We are given that there are 132 boys and 14 adults. Since the question is only asking for the ratio of adults to boys, we don't have to worry about the number of girls in this question. From here, we see that the question is asking for the ratio of adults to boys, so we put it in that exact order. Our answer is 14 to 132. I hope this helps and please don't hesitate to reach out with more questions!

If h(x) is the parent function, which equation describes the function song shifted 3 units left and 5 units down?​

Answers

Answer:

h(x + 3) - 5

Step-by-step explanation:

Given function h(x).

Shift left:

h(x) → h(x + 3)

Shift down:

h(x + 3) → h(x + 3) - 5

Given function is,

→ h(x)

As we shift left,

→ h(x) = h(x + 3)

As we shift down,

→ h(x + 3) = h(x+3)-5

Then the equation is,

→ h(x+3)-5

It is correct answer.

a pie chart is divided into four sectors in fig. 12.42. Each sector represents a percentage of the whole. The two larger sectors are equal and each represents x%. What is the angle subtended by one of those larger sectors ?​

Answers

Answer:

Angle formed by the sector measuring x% will be 126°.

Step-by-step explanation:

Since, sum of all sectors formed in a circle is 100%.

By adding the measures of all the sectors,

x + x + 21 + 9 = 100

2x + 30 = 100

2x = 70

x = 35%

Now we know sum of all the central angles formed at the center of a circle = 360°

Therefore, angle formed by x% = 360° × 35%

                                                    = [tex]\frac{360\times 35}{100}[/tex]

                                                    = 126°

Thane Company is interested in establishing the relationship between electricity costs and machine hours. Data have been collected and a regression analysis prepared using Excel. The monthly data and the regression output follow:


Month Machine Hours Electricity Costs
January 2,300 $ 19,100
February 2,700 $ 22,400
March 1,700 $ 14,200
April 2,900 $ 24,400
May 3,600 $ 28,950
June 3,100 $ 23,400
July 3,900 $ 25,450
August 3,300 $ 23,450
September 1,800 $ 16,900
October 3,500 $ 27,400
November 4,500 $ 32,400
December 4,000 $ 28,450


Summary Output
Regression Statistics
Multiple R 0.957
R Square 0.917
Adjusted R2 0.908
Standard Error 1,586.26
Observations 12.00


Coefficients Standard Error t Stat P-value Lower 95% Upper 95%
Intercept 5,970.52 1,766.77 3.38 0.01 2,033.90 9,907.13
Machine Hours 5.76 0.55 10.49 0.00 4.54 6.98

The percent of the total variance that can be explained by the regression is:

Answers

Answer:

0.924

Step-by-step explanation:

R² = 0.854

R = √0.854

R = 0.924

Hence, the correlation Coefficient of electricity tarrif is 0.924 ; this correlation Coefficient value, depicts a strong positive correlation between machine hours and cost of electricity. And can he interpreted to mean that ; Electricity tarrif increases as machine hours increases and also decreases as machine hours decreases.

what is answer if 2xyx5​

Answers

Answer:

Answer is 3bu2(DeEZ)=1

Step-by-step explanation:

An economic instructor at UCF is interested in the relationship between hours spent studying and total points earned in a course. Data collected on 11 students who took the course last semester follow:

# of observation(s) n = 30
# of independent variable(s) = 1
SSR = 1,297 SSE= 920

Required:
Find the F test statistic.

Answers

Answer:

[tex]F = 39.47[/tex]

Step-by-step explanation:

Given

[tex]n = 30[/tex] --- observations

[tex]p = 1[/tex] -- variables

[tex]SSR = 1,297[/tex]

[tex]SSE= 920[/tex]

Required

The F statistic

This is calculated using:

[tex]F = \frac{SSR}{p} \div \frac{SSE}{n - p -1}[/tex]

[tex]F = \frac{1297}{1} \div \frac{920}{30 - 1 -1}[/tex]

[tex]F = \frac{1297}{1} \div \frac{920}{28}[/tex]

[tex]F = 1297 \div \frac{920}{28}[/tex]

Rewrite as:

[tex]F = 1297 * \frac{28}{920}[/tex]

[tex]F = \frac{1297 *28}{920}[/tex]

[tex]F = \frac{36316}{920}[/tex]

[tex]F = 39.47[/tex]

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Assume the expected return on the market is 6 percent and the risk-free rate is 4 percent. What is the expected return for a stock with a beta equal to 2.00 Which of the following statements is not true? A. Avoiding contact with the blood of another person can prevent communicable diseases from spreading, but other bodily fluids pose no risk. B. Maintaining doctor visits for regular examinations can help you to detect communicable diseases early and avoid spreading them to others. C. Safe food handling and preparation of food is one way that you can help to prevent contracting and spreading some communicable diseases. D. To prevent communicable diseases from spreading, you should wash your hands after touching animals and make sure pets receive routine veterinary care. Two magnets are stuck together. What might you have to do to get them to separate? A. A plan for mass casualty incidents should include protective actions to reduce vulnerabilities, response actions to minimize negative consequences, and post incident actions to promote community recovery. B. A partnership approach to planning for mass casualty incidents helps to ensure that the plans for your organization are compatible with those of the agencies that would respond if an incident occurred. C. When an organization is planning for mass casualty incidents, an effective approach is to request law enforcement personnel to develop a separate plan for mass casualty incidents for the organization. D. It is important to customize your emergency plan to reflect the risks, realities, and resources that characterize the local area and your own organization. Give 2 reasons why the former dictator, Batista was not popular among the Cuban people Which statement would have most likely been made by someone associatedwith the NAACP during the 1960s? ng 40\%; \$4.400 A company is considering the purchase of a new machine for $ 63,000 . Management predicts that the machine can produce sales of $ 17,500 each year for the next 10 years . Expenses are expected to include direct materials , direct labor , and factory overhead totaling 6,500 per year including depreciation of per year . Income tax expense is per year based on a tax rate of What the payback period for the new machine In an extensive study involving thousands of British children, Arden and Plomin (2006) found significantly higher variance in the intelligence scores for males than for females. Following are hypothetical data, similar to the results obtained in the study. Note that the scores are not regular IQ scores but have been standardized so that the entire sample has a mean of M 5 10 and a standard deviation of s 5 2. a. Calculate the mean and the standard deviation for the sample of n 5 8 females and for the sample of n 5 8 males. b. Based on the means and the standard deviations, describe the differences in intelligence scores for males and females. The following information is available for Lock-Tite Company, which produces special-order security products and uses a job order costing system. 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Mark has diabetes and needs to undergo dialysis twice a week. Dialysis purifies the blood by removing waste and excess water from the blood. Which body system does dialysis perform a function for? helppppppppppppppppppppp plzzzzz Someone please help me with this math problem? A chocolate factory uses 16 of a bag of cocoa butter in each packet of chocolate. The factory used 13 of a bag of cocoa butter today. How many packets of chocolates did the factory make? A candy company fills a package of candy with individually wrapped pieces of candy. The number of pieces of candy per package varies because the package is sold by weight. The company wants to estimate the number of pieces per package. Inspectors randomly sample 120 packages of this candy and count the number of pieces in each package. They find that the sample mean number of pieces is 18.72. Assume the population standard deviation of .8735. 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