Assume that the helium porosity (in percentage) of coal samples taken from any particular seam is normally distributed with true standard deviation 0.78.
(a) Compute a 95% CI for the true average porosity of a certain seam if the average porosity for 15 specimens from the seam was 4.85. (Round your answers to two decimal places.)
(b) Compute a 98% CI for true average porosity of another seam based on 11 specimens with a sample average porosity of 4.56. (Round your answers to two decimal places.)
(c) How large a sample size is necessary if the width of the 95% interval is to be 0.46? (Round your answer up to the nearest whole number.)
(d) What sample size is necessary to estimate true average porosity to within 0.18 with 99% confidence? (Round your answer up to the nearest whole number.)
Answer:
a) The 95% CI for the true average porosity of a certain seam if the average porosity for 15 specimens from the seam was 4.85 is (4.46, 5.24).
b) The 98% CI for true average porosity of another seam based on 11 specimens with a sample average porosity of 4.56 is (4.01, 5.11).
c) A sample size of 12 is needed.
d) A sample size of 125 is needed.
Step-by-step explanation:
(a) Compute a 95% CI for the true average porosity of a certain seam if the average porosity for 15 specimens from the seam was 4.85.
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 Ztable as such z has a pvalue 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 = z\frac{\sigma}{\sqrt{n}}[/tex]
In which [tex]\sigma[/tex] is the standard deviation of the population and n is the size of the sample.
[tex]M = 1.96\frac{0.78}{\sqrt{15}} = 0.39[/tex]
The lower end of the interval is the sample mean subtracted by M. So it is 4.85 - 0.39 = 4.46
The upper end of the interval is the sample mean added to M. So it is 4.85 + 0.39 = 5.24
The 95% CI for the true average porosity of a certain seam if the average porosity for 15 specimens from the seam was 4.85 is (4.46, 5.24).
(b) Compute a 98% CI for true average porosity of another seam based on 11 specimens with a sample average porosity of 4.56. (Round your answers to two decimal places.)
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 - 0.98}{2} = 0.01[/tex]
Now, we have to find z in the Ztable as such z has a pvalue of [tex]1 - \alpha[/tex].
That is z with a pvalue of [tex]1 - 0.01 = 0.99[/tex], so Z = 2.327.
Now, find the margin of error M as such
[tex]M = z\frac{\sigma}{\sqrt{n}}[/tex]
In which [tex]\sigma[/tex] is the standard deviation of the population and n is the size of the sample.
[tex]M = 2.327\frac{0.78}{\sqrt{11}} = 0.55[/tex]
The lower end of the interval is the sample mean subtracted by M. So it is 4.56 - 0.55 = 4.01
The upper end of the interval is the sample mean added to M. So it is 4.56 + 0.55 = 5.11
The 98% CI for true average porosity of another seam based on 11 specimens with a sample average porosity of 4.56 is (4.01, 5.11).
(c) How large a sample size is necessary if the width of the 95% interval is to be 0.46?
95% CI means that [tex]z = 1.96[/tex]
A sample of n is needed, and n is found when M = 0.46. So
[tex]M = z\frac{\sigma}{\sqrt{n}}[/tex]
[tex]0.46 = 1.96\frac{0.78}{\sqrt{n}}[/tex]
[tex]0.46\sqrt{n} = 1.96*0.78[/tex]
[tex](\sqrt{n})^2 = (\frac{1.96*0.78}{0.46})^2[/tex]
[tex]n = 11.05[/tex]
Rounding up
A sample size of 12 is needed.
(d) What sample size is necessary to estimate true average porosity to within 0.18 with 99% confidence?
99% CI means that [tex]z = 2.575[/tex]
A sample of n is needed, and n is found when M = 0.18. So
[tex]M = z\frac{\sigma}{\sqrt{n}}[/tex]
[tex]0.18 = 2.575\frac{0.78}{\sqrt{n}}[/tex]
[tex]0.18\sqrt{n} = 2.575*0.78[/tex]
[tex](\sqrt{n})^2 = (\frac{2.575*0.78}{0.18})^2[/tex]
[tex]n = 124.5[/tex]
Rounding up
A sample size of 125 is needed.
can someone find the slope intercept equation for this plz thanks ill give brainliest
Answer:
y = -3/4x - 1
Step-by-step explanation:
it is
Please solve this math question.
Answer:
none of these
Step-by-step explanation:
the side lengths are are 2√5/5, 2, and 4.
sin(x) = opp/hyp
sin(x) = 2/2√5
A basketball player made 16 shots for a total of 38 points during a game. Some points were worth 2 points and some were worth 3 points. Write a system of equations that models this. How many 2 and 3 point shots did he make? Write your answer as a coordinate.
Answer:
4- 3s and 2- 2s
Step-by-step explanation:
3+3+2+2+3+3
Covert 2/3 years to months
Answer:
7.9 or if you need to round it,it will be 8
Step-by-step explanation:
dont have a explanation nut i hopes this help.
Simplify the expression 9x + 5-3x + 12
6x - 7
6x + 17
12x + 17
23x
Please help
Answer:
6x + 17
Step-by-step explanation:
Combine like terms
9x - 3x = 6x
5 + 12 = 17
6x + 17
PPT HELP !!!!!!!!!!!!11
Answer:
Step-by-step explanation:
a) 1 degrees Celsius (the line matches with that number)
b) -2 degrees Celsius
c) 3.5 degrees Celsius (since its between 3 and 4 its 3.5)
d) -0.5 degrees Celsius
e) the numbers will be going by 5s: (-20,-15,-10,-5, 0, 5, 10, 15, 20, 25)
I hope this makes sense and you understand it :)
Answer plz. I'll get my points back if you put something random.
Answer:
D.
Step-by-step explanation:
Because, 60% of 2.50 (the pre-assumed cost of pizza) is 1.50.
How many distinct variables does the expression below
contain?
2x^5+xy^4-zx
62.8 in scientific notation
Answer:
6.28 x 10²
Step-by-step explanation:
first number must be greater than or equal to 1 and less than 10
if you move the decimal to the left you need to increase the power of ten by one for each move
if you move the decimal to the rightt you need to decrease the power of ten by one for each move
Can anyone solo be this?
Answer:
x = 10
Step-by-step explanation:
Angles 12x and 10x + 20 are "vertical angles," meaning that they are identical (same value). Therefore we can write the equation 12x = 10x + 20, which reduces to 2x = 20, or x = 10.
Answer:
x=10
Step-by-step explanation:
Hey There!
Those are a pair of vertical angles
Therefore they are congruent
congruent meaning identical in form
So we would setup and equation and because the angles are congruent the equation would be
12x=10x+20 and solve for x
Step 1 subtract 10x from each side
10x-10x cancels out
12x-10x=2x
now we have
2x=20
Step 2 divide each side by 2
2/2 cancels out
20/2=10
Therefore x=10
Porcupines can cause damage to wood structures by chewing them. Researchers studied a liquid repellent
designed to reduce such damage. A sample of 20 wooden blocks of the same size were treated with the
repellent and left outside in an area where porcupines are known to live. After a certain amount of time, the
blocks were inspected for the number of porcupine teeth marks visible. The data were used to create the
95 percent confidence interval (4.9,5.8).
Which of the following claims is supported by the interval?
A
The expected number of porcupine teeth marks on a wooden block treated with the
repellent is less than 5.
B
B
The expected number of porcupine teeth marks on a wooden block treated with the
repellent is 5.
с
The mean number of porcupine teeth marks on all wooden blocks treated with the
repellent is 6.
D
The mean number of porcupine teeth marks on all wooden blocks treated with the
repellent is greater than 6.
E
The mean number of porcupine teeth marks on all wooden blocks treated with the
repellent is less than 6.
Answer:
The mean number of porcupine teeth marks on all wooden blocks treated with the repellent is less than 6.
Step-by-step explanation:
The mean number of porcupine teeth marks on all wooden blocks treated with the repellent is less than 5 and 6.
Option A and E are the correct answer.
What is a confidence interval?A confidence interval is a range of values that is likely to contain the true value of an unknown parameter, such as a population means or proportion, based on a sample of data from that population.
It is a statistical measure of the degree of uncertainty or precision associated with a statistical estimate.
We have,
The 95% confidence interval for the mean number of porcupine teeth marks on wooden blocks treated with the repellent is (4.9, 5.8).
This means that we can be 95% confident that the true mean number of porcupine teeth marks on all such wooden blocks falls between 4.9 and 5.8.
Option A states that the expected number of porcupine teeth marks on a wooden block treated with the repellent is less than 5.
This claim is supported by the confidence interval since the upper limit of the interval is less than 5.
Option B states that the expected number of porcupine teeth marks on a wooden block treated with the repellent is 5.
This claim is not supported by the confidence interval, since both the lower and upper limits of the interval are greater than 5.
Option C states that the mean number of porcupine teeth marks on all wooden blocks treated with the repellent is 6.
This claim is not supported by the confidence interval, since both the lower and upper limits of the interval are less than 6.
Option D states that the mean number of porcupine teeth marks on all wooden blocks treated with the repellent is greater than 6.
This claim is not supported by the confidence interval, since the upper limit of the interval is less than 6.
Option E states that the mean number of porcupine teeth marks on all wooden blocks treated with the repellent is less than 6.
This claim is supported by the confidence interval since the upper limit of the interval is less than 6.
Therefore,
The mean number of porcupine teeth marks on all wooden blocks treated with the repellent is less than 5 and 6.
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CAMO is a rectangle with diagonals intersecting at W. WA = 4x - 3 , CW = x + 6 , and AO = 22 Find x.
Answer:
x = 3.5
Step-by-step explanation:
diagonals bisect each other so AW = OW
since AO = 22 then AW = 11
11 = 4x - 3
14 = 4x
x = 7/2 or 3 1/2
christian has a maximum of 50$ to spend on his school trip a ticket to the theme park cost 27$
Answer:
50 minus 27 is 23 so she has $23 more dollars left?
Step-by-step explanation:
7.59 x 10^5 in standard form
[tex]\huge\text{Hey there!}[/tex]
[tex]\mathsf{7.59 \times 10^5}[/tex]
[tex]\mathsf{10^5}[/tex]
[tex]\mathsf{= 10(10)(10)(10)(10)}[/tex]
[tex]\mathsf{10(10) = 100}[/tex]
[tex]\mathsf{= 100(100)(10)}[/tex]
[tex]\mathsf{100(100) = 10,000}[/tex]
[tex]\mathsf{= 10,000(100)}[/tex]
[tex]\mathsf{= 100,000}[/tex]
[tex]\mathsf{7.59(100,000)}[/tex]
[tex]\mathsf{= \bf 759,000}[/tex]
[tex]\boxed{\boxed{\huge\text{Answer: \bf 759,000}}}\huge\checkmark[/tex]
[tex]\text{Good luck on your assignment and enjoy your day!}[/tex]
~[tex]\frak{Amphitrite1040:)}[/tex]
Which fraction has the larger value? *
-3/4
-1/2
Answer:
I'm thinking it's -1 / 2
Step-by-step explanation:
not sure how but
Answer:
-1/2
Step-by-step explanation:
Why? Because 1/2 is bigger than 3/4
Complete the congruency statement for the triangles
Answer:
∆ABC ≅ ∆EDF by the SAS Congruence Theorem.
Step-by-step explanation:
<A ≅ <E,
Side length AC ≅ Side length EF
Side length AB ≅ Side length ED,
Thus, this implies that an included angle and two sides of one triangle are congruent to an included angle and 2 corresponding side lengths of the other triangle.
Therefore, we would conclude that:
∆ABC ≅ ∆EDF by the SAS Congruence Theorem.
B:
The usual monthly expenses of midas family is 3500.00 for their electric and and with bill, 10,
000 for house and 5,000.00 for their food. The rest of their income will be their savings How much
will be their savings if the couple both earn 10,000.00each
Answer:
$1,500
Step-by-step explanation:
Income - Expenses = Savings
Income = 2 × 10,000 = $20,000
Expenses = 3,500 + 10,000 + 5,000 = $18,500
$20,000 - $18,500 = $1,500 left for Savings
What is the value of x in the following equation?
7x + 5(2x – 10) = 69
Answer:
Step-by-step explanation:
7x+10x-50=69
17x=69+50
x=7
an employer pays three workers x,y,z a total amount of 6100 a month. x is paid 125% of the amount y is paid; which represent 80% of the amount z is paid. how much does x receive a month
Answer:
X earns $ 2,178.57, as does Z, while Y earns $ 1,742.85.
Step-by-step explanation:
Since an employer pays three workers X, Y and Z a total amount of $ 6100 a month, of which X is paid 125% of the amount Y is paid; which represents 80% of the amount Z is paid, to determine how much does X receive a month the following calculation must be performed:
X = 1.25Y
Y = 0.8Z
Z = Z
Z + Y + X = 6,100
Z + 0.8Z + (1.25 x 0.8Z) = 6,100
Z + 0.8Z + Z = 6,100
2.8Z = 6,100
Z = 6,100 / 2.8
Z = 2,178.57
Y = 0.8 x 2,178.57 = 1,742.85
X = 1,742.85 x 1.25 = 2,178.57
2,178.57 + 2,178.57 + 1,742.85 = X
6,099.99 = X
Thus, X earns $ 2,178.57, as does Z, while Y earns $ 1,742.85.
Brainliest will be given ASAP question below!
Answer:
3/32
Step-by-step explanation:
9/16 × 3/4=27/144=3/16×1/2=3/32
Solve for w. Only use numbers in your answer.
8w - 15 = 57
w =
Answer:
w = 9
Step-by-step explanation:
1. Add 15 from both sides: 8w = 72
2. Divide my 8: w = 9
Answer:
the answer for this question is 9
How many invitations should Tyler make each day if his goal is 122 and he already made 66 and he wants to finish in a week
What is the equation of the line that passes through the point (-6, -6) and has a
slope of - 1/3
Answer:
The equation of the line is [tex]y = -\frac{1}{3}x - 8[/tex]
Step-by-step explanation:
Equation of a line:
The equation of a line has the following format:
[tex]y = mx + b[/tex]
In which m is the slope and b is the y-intercept.
Slope of - 1/3
This means that [tex]m = -\frac{1}{3}[/tex]
So
[tex]y = -\frac{1}{3}x + b[/tex]
Through the point (-6, -6)
This means that when [tex]x = -6, y = -6[/tex]. So
[tex]y = -\frac{1}{3}x + b[/tex]
[tex]-6 = -\frac{1}{3}(-6) + b[/tex]
[tex]b + 2 = -6[/tex]
[tex]b = -8[/tex]
The equation of the line is [tex]y = -\frac{1}{3}x - 8[/tex]
Convert 20% into a fraction
ANSWER QUICKK
Answer:
1/5.
Step-by-step explanation:
20%
20/100
20/20 / 100/20
= 1/5
---
Hope this helps!
Answer:
20/100 or 1/5
Step-by-step explanation:
Imagine the percent as a lazily drawn 100. For example, 68% would also be 68/100, or simplified to 17/25
hope it helps! :3
What is the y-intercept of the line?
Answer:
28
Step-by-step explanation:
Answer: 5 is the y-intercept and -16 is the slope
22 - 17 = 5
32 - 48 = -16
Step-by-step explanation:
Simplify the following expression
6y + 8 - 2y + 5y - 9
Answer: 9y-1
:))))))))))))))))))))
7)
Which could be solved for x?
-0)
A)
2x+2
B)
3(x+ 2)
)
D)
1 / 8x = 12
Can someone please help me
Answer:
135ft^3
Step-by-step explanation:
Volume for triangular prism = 1/2bhl
v=1/2*6*5*9= 135
Cellulon, a manufacturer of home insulation, wants to develop guidelines for builders and consumers on how the thickness of the insulation in the attic of a home and the outdoor temperature affect natural gas consumption. In the laboratory, it varied the insulation thickness and temperature. A few of the findings are:
Monthly Natural Gas Consumption (cubic feet), Thickness of Insulation (inches), Outdoor Temperature (ºF),
y x1 x2
30.3 6.0 32.0
25.2 12 40
30.5 8 49
On the basis of the sample results, the regression equation is:
yˆ y^ = 57.25 − 1.07x1 − 0.64x2
According to the regression equation, the predicted Monthly Natural Gas Consumption (ŷ) can be estimated by subtracting 1.07 times the Thickness of Insulation (x1) and 0.64 times the Outdoor Temperature (x2) from 57.25.
The regression equation provided is:
ŷ = 57.25 - 1.07x1 - 0.64x2
Where:
ŷ represents the predicted value of Monthly Natural Gas Consumption (cubic feet)
x1 represents the Thickness of Insulation (inches)
x2 represents the Outdoor Temperature (ºF)
Based on the regression equation, the coefficients indicate the relationship between the independent variables (Thickness of Insulation and Outdoor Temperature) and the dependent variable (Monthly Natural Gas Consumption).
The coefficient for x1 (Thickness of Insulation) is -1.07. This means that, holding the Outdoor Temperature constant, for every 1-inch increase in the Thickness of Insulation, the predicted Monthly Natural Gas Consumption is expected to decrease by 1.07 cubic feet.
The coefficient for x2 (Outdoor Temperature) is -0.64. This means that, holding the Thickness of Insulation constant, for every 1-degree Fahrenheit increase in the Outdoor Temperature, the predicted Monthly Natural Gas Consumption is expected to decrease by 0.64 cubic feet.
The constant term in the equation is 57.25. This represents the predicted Monthly Natural Gas Consumption when both the Thickness of Insulation and Outdoor Temperature are zero.
for such more question on regression equation
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