An investigator compares the durability of two different compounds used in the manufacture of a certain automobile brake lining. A sample of 243 brakes using Compound 1 yields an average brake life of 37,866 miles. A sample of 268 brakes using Compound 2 yields an average brake life of 45,789 miles. Assume that the population standard deviation for Compound 1 is 4414 miles, while the population standard deviation for Compound 2 is 2368 miles. Determine the 95% confidence interval for the true difference between average lifetimes for brakes using Compound 1 and brakes using Compound 2. Step 2 of 3 : Calculate the margin of error of a confidence interval for the difference between the two population means. Round your answer to six decimal places.
Answer:
The margin of error is of 623.2016.
The 95% confidence interval for the true difference between average lifetimes for brakes using Compound 1 and brakes using Compound 2 is (-8546.2016, -7299.7984).
Step-by-step explanation:
Before building the confidence interval, we need to understand the central limit theorem, and subtraction between normal variables.
Central Limit Theorem
The Central Limit Theorem estabilishes 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 subtraction of the means while the standard deviation is the square root of the sum of the variances.
A sample of 243 brakes using Compound 1 yields an average brake life of 37,866 miles. The population standard deviation for Compound 1 is 4414 miles.
This means that [tex]\mu_1 = 37866, s_1 = \frac{4414}{\sqrt{243}} = 283.16[/tex]
A sample of 268 brakes using Compound 2 yields an average brake life of 45,789 miles. The population standard deviation for Compound 2 is 2368 miles.
This means that [tex]\mu_2 = 45789, s_2 = \frac{2368}{\sqrt{268}} = 144.65[/tex]
Distribution of the difference between average lifetimes for brakes using Compound 1 and brakes using Compound 2.
The mean is:
[tex]\mu = \mu_1 - \mu_2 = 37866 - 45789 = -7923[/tex]
The standard deviation is:
[tex]s = \sqrt{s_1^2 + s_2^2} = \sqrt{283.16^2 + 144.64^2} = 317.96[/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 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 = zs[/tex]
[tex]M = 1.96*317.96 = 623.2016[/tex]
The margin of error is of 623.2016.
The lower end of the interval is the sample mean subtracted by M. So it is -7923 - 623.2016 = -8546.2016
The upper end of the interval is the sample mean added to M. So it is -7923 + 623.2016 = -7299.7984
The 95% confidence interval for the true difference between average lifetimes for brakes using Compound 1 and brakes using Compound 2 is (-8546.2016, -7299.7984).
What is 1/3 of $4.89 dollars
Answer:
im pretty sure its 1.63
Step-by-step explanation:
lmk if im wrong
Can someone here please help me out?
Answer:
hope you can now substitute and find y
Bob the builder eat no fewer then three donuts. What is the inequality?
Answer:
3
Step-by-step explanation:
I think
Answer:
less than or equal to 3
Step-by-step explanation:
An inclined walkway leading to a new building is to rise 11 inches for each horizontal distance of 22 feet. Write this slope as a grade. (Round to the nearest tenth of a percent if necessary.)
Answer:
4.2%
Step-by-step explanation:
The horizontal distance, x (Run) = 22 feets
Rise, vertical distance, y = 11 inches
The slope is the ratio of the vertical to the horizontal distance, Rise to Run
Slope = Rise / Run
Converting to the same unit ;
Foot to inches
1 foot = 12 inches
Hence, x = 22 feets = (12 * 22) = 264 inches
Slope = Rise / Run = 11 / 264 = 0.04167
Slope = 0.04167 * 100% = 4.167%
Write an equation for the sum of x and 3 minus 2 is 12
Answer:
x + (3-2) = 12
Step-by-step explanation:
x + (3-2) = 12
or x + 1 = 12
so x = 11
A spinner has five sections labeled a,b,c,d,e. The spinner is spun 45 times
Answer:
40
Step-by-step explanation: pls I need points make brainpy
Use the picture below and determine which of the lines or line segments 20 points
is/are a diameter
mA
VE
Line m
Line Segment BC
Ο Ο Ο Ο Ο
Line Sesnent AB or AC
Line Segment DE
Line 1
Suppose {an) is an arithmetic sequence with a16=12 and a7=30. Find a9.
Answer:
a9 = 26
Step-by-step explanation:
nth term of an arithmetic sequence an = a + (n-1)d
a16 = a+15d = 12.... 1
a7 = a+6d = 30.....2
Subtract
15d - 6d = 12 - 30
9d = -18
d =-18/9
d = -2
Substitute d = -2 into 1
a + 15d = 12
a+15(-2) = 12
a - 30 = 12
a = 12 + 30
a = 42
Get a9;
a9 = a+8d
a9 = 42+8(-2)
a9 = 42 - 16
a9 = 26
hence the 9th term of the sequence is 26
expanded form :32,456
Answer:
30,000 + 2,000 + 400 + 50 + 6
Step-by-step explanation:
[tex]\text{The expanded form of 32,456 would be 30,000 + 2,000 + 4,000 + 50 + 6.}[/tex]
[tex]\text{We would have to identify what each number stands for.}[/tex]
[tex]\text{For example, 3 in 32,456 stands for 30,000.}[/tex]
[tex]\text{Hence, following this rule, we can conclude that the answer above is correct.}[/tex]
[tex]\text{I hope I helped you suceed!}[/tex]
A student formed a pattern in which each term is represented by a sum. The first four terms of the pattern are shown below Which expression can be used to determine the value of the sum in any term, n
Answer:
n2
Step-by-step explanation:i did this last year
Can I please get help with this math problem? Thanks in advance.
Answer:
answer: scale factor is 3
Hope this helps
Answer:
ans :; scale factor is 3
this is the correct ans.
can someone help, please :)
GIVING BRAINLIEST
Explain your reasoning.
3(n + 2) = 9(6 - n)
Answer: n = 4
Step-by-step explanation:
Divide both sides by 3
n+2=3(6−n)
Expand
n+2=18−3n
Subtract 2 from both sides
n=18−3n−2
Simplify 18−3n−2 to −3n+16.
n=−3n+16
Add 3n to both sides
n+3n=16
Simplify n+3n to 4n
4n=16
Divide both sides by 4
n= 4/16
Simplify 16/4 to4
n=4
Jon throws a ball into the air off a platform. The height of the ball is given by y equal minus 2 x to the power of 2 plus 11 x plus 21 where y is the height, in feet, above the ground when the ball has traveled a horizontal distance of x feet. What is the factored form of the expression that could be used to find out how far the ball has traveled horizontally when it hits the ground?
A. (x+7)(-2X+3)
B. (x-7)(-2x-3)
C.(2x+7)(x+3)
D. (2x-7)(-x-3)
Answer:
B (-2x - 3 )(x - 7) = (x - 7)(-2x - 3 )
Step-by-step explanation:
y = -2x² + 11x + 21
find x when y is zero (the ground)
(-2x - 3 )(x - 7) = 0
(-2x - 3 ) = 0, (x - 7) = 0
x = -1.5 and x = 7 since Jon did not throw the ball behind him (remember he is standing on a platform) the only possible answer is 7 feet in front of him, but they the question didn't ask for x, so I would answer B. The answer I got and multiplicans are in reverse order from their choice.
The factored form of the expression that could be used to find out how far the ball has traveled horizontally when it hits the ground is (x-7)(-2x-3)
What is quadratic equation?A quadratic equation is a second-order polynomial equation in a single variable x , ax² +bx+c=0. with a ≠ 0 .
Given that Jon throws a ball into the air off a platform.
The height of the ball is given by y equal minus 2 x to the power of 2 plus 11 x plus 21
y= -2x² + 11x + 21.
Let us factor out the equation by quadratic equation
-2x² + 11x + 21
When we factor out the equation becomes as (x-7)(-2x-3)
Let us verify the solution by applying distribution property
-2x²-3x+14x+21
-2x²+11x+21
Hence, (x-7)(-2x-3) is the factored form of the expression that could be used to find out how far the ball has traveled horizontally when it hits the ground.
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please help me here im begging you it won't let me just skip it
Answer:
ABCD in statement and the other in reasoning
Step-by-step explanation:
Write equivalent fractions for 1 2/3 and 1 7/8 using 24 as the common denominator 2 24 7 1 0
Answer:
2×8=16
7×3=21
2/3 + 7/8 = 16/24 + 21/24
What is -13 decreased by 9
Answer:
-4
Step-by-step explanation:
Answer:
-22
Step-by-step explanation:
-13 - 9
When both the numbers have the same sign, we add them. After adding we put the same sign of the numbers to the answer
-13-9 = -22PLZ FULL ANSWER
Maria has the following scores on exams in her social studies class: 86, 75, 97, 58, 94, and 58. Find the mean, median, and mode of the scores. Should Maria’s social studies teacher use the mean, median, or mode of the exam scores to convince Maria that she needs to study more regularly for her exams?
Answer:
The mean is 78
The Median is 80.5
And The Mode is 58.
Step-by-step explanation:
(Mean) 86,75,97,58,94, and 58 equal 468. Divide it by 6 (The Total Of All The Numbers) and it gives you 78.
(Mode) Find the number that occurs the most which would be 58.
(Median) Put the numbers in order. Order: 58,58,75,86,94,97. Next, your supposed to find the number in the middle, but since there are 2(75 and 86.)
Add them together and you get 161. After that, divide them by 2 and it'll give you 80.5
By the way, if the number of numbers in the problem add up to be an even number, divide it by 2 and find the average. If it's odd, divide it by 2 and round it up to get to the median.
So yes, the teacher should use the scores to convince Maria that she needs to study more regularly for her exams.
The mean, median, or mode of the exam scores is 78, 86 and 58
What is Mean, median and Mode?The mean (average) of a data set is found by adding all numbers in the data set and then dividing by the number of values in the set.
The median is the middle value when a data set is ordered from least to greatest.
The mode is the number that occurs most often in a data set.
Given data: 58, 58, 75, 86, 94, 97
1. Mean= sum of observation/ Total number observation
= 58+58+75+86+94+97/6
=468/6
=78
2. Median,
Since, n is even
median= (n/2)+ 1
= 6/2 + 1
= 3+1
=4 th term= 86
3. Mode: Mode is the repeating data
mode= 58
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For his birthday , Aaron received four stamps for his collection . his collection already contained eight times that number of stamps. Before pasting the stamps into albums , Aaron divide them equally into three envelope. Which numerical expression models the number of stamps in each envelope? A 12÷3 B 4+32÷3 C (4+32)÷3 D 12×4÷4
Answer:
C
Step-by-step explanation:
Aaron received four stamps. He already had eight times as much. 32 + 4. Before pasting the stamps into albums, Aaron divides them equally into three envelopes. (32 + 4) ÷ 3.
You determine that you can make 72 donuts in 2 hours. At that rate, how
many donuts can you make in 8 hours?
Answer:
576
Step-by-step explanation:
A bag contains 2 red, 4 blue, and 4 yellow marbles. What is the probability of pulling a red marble, putting the marble back, and then pulling a blue marble?\
Answer:
Di ko po alam sorry
Step-by-step explanation:
Di ko alam putaenamo
the sum of the first four terms of an A.p is 62.if the difference between 4 terms and 2nd terms is 14. find the first term and common difference
Answer:
-2 -4 -6 -8
Step-by-step explanation:
I got the answer off of khan academy
Sandy is getting ready for the day. She can wear either a balck or white shirt and then either pants, shorts, or a skirt. Create a tree diagram or label all the combinations she can make. How many are there total?
Select the statement that correctly describes a normal distribution.
a. It is a negatively skewed distribution, as the extreme values are less than the median.
b. It is a symmetric distribution, as the mean and the median are the same.
c. It is a positively skewed distribution, as the extreme values are greater than the median.
d. It is a uniform distribution, as all of the values have equal frequency.
Answer:
b. It is a symmetric distribution, as the mean and the median are the same.
Step-by-step explanation:
Normal distribution:
The biggest characteristic of the normal distribution is that it's symmetric, that is, 50% of the values are below the mean and 50% are above, which means that the mean is the same as the median.
This means that the correct answer is given by option b.
(05.03 LC) What is the equation of a horizontal line passing through the point (2, 10)? (5 points)
Answer:
y=10
Step-by-step explanation: a horizontal line has no slope
Stock in Macy's costs $25.75 per share. Hector buys 200 shares of Macy's
through his broker who charges a commission of $25.75. How much did George
pay in total to purchase the stock?
Answer: $5175.75
Step-by-step explanation:
The amount that is paid in total to buy the stock will be gotten through the addition of the cost of the shares and the commission paid. This will be:
= (200 × $25.75) + $25.75
= $5150 + $25.75
= $5175.75
Therefore, the total amount that is paid to buy the stock will be $5175.75.
Determine the median of the following numbers: 8, 11, 11, 12, 13, 15, 16, 16, 18, 21
Answer:
The median of the following numbers is 14
Step-by-step explanation:
PLEASE TELL ME PLEASE
Answer: D!! also 35% are spotted
Answer:
The answer is a.
Step-by-step explanation:
This is because the percent is out of 100 and the flock of spotted sheep is placed in the numerator.
What is the volume of a rectangular prism with a length of 2 1/2 inch width of 4 inches, and a height of 3 inches? * 21: 36 cu, in O 30 cu in 9.5 cu in 0 26 cu.in
Answer:
30 cubic inch
Step-by-step explanation: