Fuel Efficiency of Cars and Trucks Since 1975 the average fuel efficiency of U.S. cars and light trucks (SUVs) has increased from 13.5 to 25.8 mpg, an increase of over 90%! A random sample of 40 cars from a large community got a mean mileage of 28.1 mpg per vehicle. The population standard deviation is 4.7 mpg. Estimate the true mean gas mileage with 95% confidence.

Answers

Answer 1

Answer:

[tex]28.1-1.96\frac{4.7}{\sqrt{40}}=26.64[/tex]    

[tex]28.1+ 1.96\frac{4.7}{\sqrt{40}}=29.56[/tex]    

We are confident at 95% of confidence that the true mean for the mpg is between 26.64 and 29.56. And since the lower limit from the confidence interval is highert than 25.8 then we can conclude that we have a significant increase from 1975

Step-by-step explanation:

Information given

[tex]\bar X= 28.1[/tex] represent the sample mean

[tex]\mu[/tex] population mean

[tex]\sigma =4.7[/tex] represent the population standard deviation

n=40 represent the sample size  

Confidence interval

The confidence interval for the mean is given by the following formula:

[tex]\bar X \pm z_{\alpha/2}\frac{\sigma}{\sqrt{n}}[/tex]   (1)

The Confidence level is is 0.95 or 95%, the significance would be [tex]\alpha=0.05[/tex] and [tex]\alpha/2 =0.025[/tex], and we can calculate the critical value using the normal standard distribution and we got [tex]z_{\alpha/2}=1.96[/tex]

And replacing we got:

[tex]28.1-1.96\frac{4.7}{\sqrt{40}}=26.64[/tex]    

[tex]28.1+ 1.96\frac{4.7}{\sqrt{40}}=29.56[/tex]    

We are confident at 95% of confidence that the true mean for the mpg is between 26.64 and 29.56. And since the lower limit from the confidence interval is highert than 25.8 then we can conclude that we have a significant increase from 1975


Related Questions

Select and place the symbol that will make the statement true |-a| |a|

Answers

Answer:

|-a|=|a|

Step-by-step explanation:

The lines beside the a's mean that you are trying to find the absolute value of what's inside. The absolute value of something is the distance it is from 0. You can't have a negative distance so anything inside of absolute value line are positive.

Therefor this is how we can solve this.

|-a| __ |a|

  a __ a

a=a

Explain how to find the product of 3/7 X 7/9 . Use complete sentences in your answer.

Answers

Answer:

1/3 simplifed.

Step-by-step explanation:

To find the product of 3/7*7/9. We can multiply top and bottom. Top: 3*7=21 Bottom: 7*9=63. Our final answer is just the Top/Bottom= 21/63. We can also simplify this into 1/3 which is our final answer.

A sample of carbon-12 has a mass of 6.00 g. How many atoms of carbon-12 are in the sample?
3.01 x 10^23
6.02 x 10^23
1.20 x 10^24
3.60 x 10^24

Answers

The answer is third one

Answer:

The answer is 3.01 x 10’23

Step-by-step explanation:

I got the answer to wrong and guessed the first one and it was correct

B point is (-5,-4) moves through the translation (x+1 , y-3) what will be the coordinates of B

Answers

Answer:

(-4,-7)

Step-by-step explanation:

Adding 1 to the x and subtracting 3 from the y we get

-5+1= -4

And

-4-3= -7

Complete the statements with equal to, greater than, or less than. 5 6 × 6 9 is ? 5 6 . 6 × 5 6 is ? 5 6 . 5 6 × 9 9 is ? 5 6 . 5 6 × 8 7 is ? 5 6 . 7 7 × 5 6 is ? 5 6 . 5 6 × 5 6 is ? 5 6 .

Answers

Answer:

someone already answered

Step-by-step explanation:

srry

30 points. WILL MARK BRAINLIEST

Which would be a correct first step to solve the following system of equations using the elimination method?

x + 3y = 16
2x + y = -18

A: Add the two equations together

B: Subtract the first equation from the second equation

C: Multiply the first equation by -2

D: Multiply the second equation by 2

Answers

Answer:

C: Multiply the first equation by -2

Step-by-step explanation:

-2 * (x + 3y = 16) = -2x-6y=-32

The resulting equation would be -2x-6y=-32

In the next if you add the two equations, you will successfuly eliminate x and can now solve for y.

-2x-6y=-32

2x + y = -18

Answer:

c

Step-by-step explanation:

x+3y=16________________eqn 1

2x+y=-18_______________eqn 2

multiply first equation by - 2

-2(x+3y=16)

-2x-6y= -32______________eqn 3

using elimination method

-2x-6y= -32

+

2x+y= -18

0-5y= -50

-5y= -50

divide both sides by -5

-5y/5= -50/5

y=10

substitute y in eqn 2 to find the value of x

2x+y= -18

2x+(10)= -18

2x+10= -18

2x= -18-10

2x= -28

divide both sides by 2

2x/2= -28/2

x= -14

If z=32 and z/2+37=x what is x

Answers

Answer:

53

Step-by-step explanation:

Plugging in 32 for z, you get:

(32)/2+37=x

16+37=x

x=53

Hope this helps!

The solution of the linear equation z/2 + 37 = x at x at z = 32 will be 53.

What is the solution to the equation?

The distribution of weights to the variables involved that establishes the equilibrium in the calculation is referred to as a result.

A relationship between two or more parameters that, when shown on a graph, produces a linear model. The degree of the variable will be one.

The linear equation is given below.

z/2 + 37 = x

Then the solution of the linear equation z/2 + 37 = x at z = 32. Then the equation will be

x = 32/2 + 37

x = 16 + 37

x = 53

Thus, the solution of the linear equation z/2 + 37 = x at z = 32 will be 53.

More about the solution of the equation link is given below.

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An urn contains 8 black and 6 pink balls. Five balls are randomly drawn from from the urn in succession, with replacement. That is, after each draw, the selected ball is returned to the urn. What is the probabillity that all the 5 balls drawn from the urn are pink? Round your answer to 3 decimal places. (IF necessary, consult a list of formulas)

Answers

Answer:

2.143

Step-by-step explanation:

An urn contains 8 black and;

6 pink balls.

5 balls are randomly drawn from the urn in succession, with replacement.

What is the probability that all the 5 balls drawn from the urn are pink?

The probability of drawing a pink ball in the first draw is 6/14The probability of drawing a pink ball in the second draw is 6/14The probability of drawing a pink ball in the third draw is 6/14The probability of drawing a pink ball in the fourth draw is 6/14The probability of drawing a pink ball in the fifth draw is 6/14

The probability that all the 5 balls drawn is pink is 5 × 6/14 = 30/14 = 2.143 (rounded off to 3 decimal places)

The probability of drawing 5 pink balls is 0.271

Since the balls are replaced after each draw, the probability of drawing a pink ball each time is always  

6/14

=3/7

Since we are drawing 5 balls, the probability of drawing 5 pink balls with replacement is

[tex](3/7)^{5}[/tex]

≈0.2706

 

Rounding to 3 decimal places, the probability is  0.271

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You are going to sell your Samsung so you can get the new iPhone. You purchased your Samsung 2 years ago for $200. It's
value decreases at a rate of 2% each month. To the nearest dollar, how much is your Samsung worth now?

Answers

Answer:

[tex]\boxed{\ 123 \ dollars\ }[/tex]

Step-by-step explanation:

its value decreases at a rate of 2% each month

in 2 years there are 12*2=24 months

so the Samsung worth [tex]200(0.98)^{24}\\[/tex]

it gives 123 rounded to the nearest dollar

Answer:

$123

Step-by-step explanation:

initial price= $200

value decrease rate= 2% = 0.98 times a month

time = 2 years

current value= $200*0.98²⁴= $123

Consider a manufacturing process with a quality inspection station. In the past, 10% of parts are defective. As soon as one defective part is found, the process is stopped. If 6 parts have been inspected without finding a defective part, what is the probability that at least 9 total parts will be inspected before the process is stopped

Answers

Answer:

0.9

Step-by-step explanation:

10% is equal to 0.1

The probability of having defective parts in a pile of parts is 0.1

Before the process is stopped, 1 part has to be defective.

In a pile of 9 parts, the probability that a part is defective 0.1 of 9, which is = 0.9 hence, approximately one (1) part will be defective in a pile of 9 parts and the process will be stopped.

Since there was no defective part among the first 6 parts, P(d) was 0

That is, probability of a defective part was zero.

Design and complete a frequency table for Belinda.
Belinda ask 20 people, how many hours of TV did you watch last week?

Here is the results
3,17,4,4,6,11,14,14,1,20,9,8,9,6,12,7,8,13,13,9.
Belinda wants to show these result in a frequency table.
She will use 4 equal groups.
The first group will start with 1 hour and the last group will end with 20 hours.

Answers

Answer:

Step-by-step explanation:

Since she will use 4 groups or class intervals, the the class width would be 20/4 = 5 hours

The class groups would be

1 to 5

5 to 10

10 to 15

15 to 20

The class mark for each class is the average of the minimum and maximum value of each class. Therefore, the class marks are

(1 + 5)/2 = 3

(5 + 10)/2 = 7.5

(10 + 15)/2 = 12.5

(15 + 20)/2 = 17.5

The frequency table would be

Class group Frequency

1 - 5 4

5 - 10 8

10 - 15 6

15 - 20 2

The total frequency is 4 + 8 + 6 + 2 = 20

Graph: y = 3/4 x + 5

Answers

Answer: The graph is

The graph is plotted and attached.

What is a Function?

A function is a law that relates a dependent and an independent variable.

The function is y = 3/4 x + 5

The slope of the line is (3/4)

and the y intercept is 5.

The graph is plotted and attached with the answer.

To know more about Function

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What is the measure of XYZ?
please help me out

Answers

Answer:

The answer is C.

Step-by-step explanation:

You have to divide it by 2 :

∠XYZ = 148° ÷ 2

= 74°

An English teacher needs to pick 10 books to put on her reading list for the next school year, and she needs to plan the order in which they should be read. She has narrowed down her choices to 4 novels, 6 plays, 8 poetry books, and 4 nonfiction books. Step 1 of 2 : If she wants to include no more than 3 poetry books, how many different reading schedules are possible? Express your answer in scientific notation rounding to the hundredths place.

Answers

Answer:

the number of possible reading schedules is 1.064301638 × 10¹²

Step-by-step explanation:

Given that :

The English teacher needs to pick 10 books to put on her reading list for the next school year.

If the English teacher picks at most  3 poetry books i.e no  more than 3 poetry books from 8 books. and other books are picked from (6+4+4 ) = 14 books

Thus; the number of ways to pick the books are :

[tex]\left[\begin{array}{c}8\\0\\ \end{array}\right] \ \left[\begin{array}{c}14\\10\\ \end{array}\right]+ \left[\begin{array}{c}8\\1\\ \end{array}\right] \left[\begin{array}{c}14\\9\\ \end{array}\right] + \left[\begin{array}{c}8\\2\\ \end{array}\right] \left[\begin{array}{c}14\\8\\ \end{array}\right] + \left[\begin{array}{c}8\\3\\ \end{array}\right] \left[\begin{array}{c}14\\7 \\ \end{array}\right][/tex]

[tex]= [ \dfrac{8!}{0!(8-0)!}* \dfrac{14!}{10!(14-10!)} ] + [ \dfrac{8!}{1!(8-1)!}* \dfrac{14!}{9!(14-9)!}]+ [ \dfrac{8!}{2!(8-2)!}* \dfrac{14!}{8!(14-8)!}] + [ \dfrac{8!}{3!(8-3)!}* \dfrac{14!}{7!(14-7)!}][/tex]

[tex]= [ 1*1001]+[8*2002]+[28*3003]+[56*3432][/tex]

[tex]\mathbf{= 293293}[/tex]

However, to determine how many reading schedules that are possible we use the relation:

Number of ways to pick a book × [tex]^{10}P_{10}[/tex]

[tex]= 293293* \dfrac{10!}{(10-10)!}[/tex]

= 293293 ×  10!

= 1.064301638 × 10¹²

Thus , the number of possible reading schedules is 1.064301638 × 10¹²

Determine whether the geometric series 192 + 48 + 12 + ... converges or diverges, and identify the sum if it exists.


A.) Converges: 768

B.) Diverges

C.) Converges; 64

D.) Converges; 256

Answers

Answer:

D.) Converges; 256

Step-by-step explanation:

x0= 192

x1 = 48 = 192/4

x2 = 12 = 192/(4 x 4)

Therefore, this series can be written as:

[tex]x_n = \frac{192}{4^n}[/tex]

Applying limits at infinity:

[tex]\lim_{n \to \infty} x_n= \lim_{n \to \infty} (\frac{192}{4^n}) = \frac{192}{\infty}=0[/tex]

Since the terms of the series tend to zero, we can affirm that the series converges.

The sum of an infinite converging series is:

[tex]S=\frac{x_0}{1-r} \\S=\frac{192}{1-\frac{1}{4} }\\S=256[/tex]

Thus, the answer is D.) Converges; 256

Solve:

|x-7|<-1.

zero solutions
one solution
infinite solutions
all real numbers

Answers

Step-by-step explanation:

In mathematics, the absolute value |x|, is the non-negative result of x without regard to its sign.

An absolute function, can never have a negative result.

By this alone, you can solve the question because the inequality is false, and therefore there are zero solutions.

Please see the attachment of f(x) = |x - 7|.

When you look at the graph, you can easily confirm that there is no value which can result in a negative y- coordinate like -2. In fact, that is the whole purpose of any absolute value or function. The result of an absolute function can never be negative.

Find and of the function = − −( − ).​

Answers

Answer:

Thats not possible

Step-by-step explanation:

There is no:

numbersvariablesonly negative signs

In a survey, participants were asked how much confidence they had in the economy.
The results were as follows:



Response Number

A great 3,187
deal

Some
9,120

Hardly 5,149
any



What is the probability that a sampled person has either some confidence or a great
deal of confidence in the economy? Write only a number as your answer. Round to
two decimal places (for example: 0.43). Do not write as a percentage.

Answers

Answer:

0.71

Step-by-step explanation:

Great Deal or Some = 12,307

Total Participants = 17,456

Probability = 12,307/17,456 = 0.71

Simplify 1 · 0 - . can someone please help out

Answers

Answer:

That would be just 0 because anything multiplied by 0 is 0.

It would be 0. And will need to simplify

Please help . I’ll mark you as brainliest if correct !

Answers

Answer:

4 ( a+2)

Step-by-step explanation:

The average rate of change is

(f(a) - f(2))/(a-2)

f(a) = 4a^2 -8

f(2) = 4*2^2 -8 = 4*4 -8 = 16-8 = 8

(4a^2 - 8  - 8))/(a-2)

(4a^2 -16) / (a-2)

Factor the numerator

4( a^2 -4) / (a-2)

4( a-2)(a+2) / (a-2)

Cancel

4 ( a+2)

URGERNT!!!PLS AT LEAST TAKE A LOOK!!! SHARE YO SMARTNESSS!! AND BLESS YOUR GRADES!

Which sign explains the relationship between m∠1 and m∠2 in the diagram?
A) not equal to
B) >
C) <
D) =

Answers

Answer:

Dear Laura Ramirez

Answer to your query is provided below

Option D is correct.

Reason - Because of Hinge and Converse of Hinge theorem

Please answer this correctly without making mistakes

Answers

Answer:

589

Step-by-step explanation:

l x w

19x11

5x31

5x45

589

Answer:

589 is the answer

What is the answerrrrrrrrrrrr :(((((((((((

Answers

Answer: The answer is choice 3

Step-by-step explanation:

i think the answer is c

Step-by-step explanation:

i don't think u would want a whole explanation

Let x represent the number. Use the given conditions to write an equation. Solve the equation and find the number.
The product of 8 and a number is 96. Find the number.
Write an equation for the given conditions.

Answers

Answer:

12

Step-by-step explanation:

8x=96

x=96/8

x=12

Answer:

12

Step-by-step explanation:

8x=96

96/8

x=12

so the the product of 8and 12=96

Is 3/5 A.irrational, B.rational, C.natural and whole, or D.natural, whole integer and rational

Answers

Answer:

B

Step-by-step explanation:

3/5 is a fraction, meaning it isn't irrational, natural, whole or an integer, therefore the answer is rational (B).

Answer:

B.rational

Step-by-step explanation:

3/5 is written as a fraction so it is a rational number

It is not a whole number since it is a reduced fraction that is less than 1

solve 5(x+4)<75 sdsdsd

Answers

Answer:

x < 11

Step-by-step explanation:

[tex]5(x+4)<75 \\ open \: the \: bracket \: using \: 5 \\ 5x + 20 < 75 \\ subtract \: - 20 \: from \: both \: sides \: [/tex]

[tex]5x + 20 - 20 < 75 - 20 \\ 5x < 55 \\ divide \: both \: sides \: of \: the \: equation \: \\ by \: 5[/tex]

[tex] \frac{5x}{5} < \frac{55}{5} \\ x < 11[/tex]

The required solution of inequality is,

⇒ x < 11

We have to simplify the expression,

⇒ 5 (x + 4) < 75

We can simplify it by definition of inequality as,

⇒ 5 (x + 4) < 75

⇒ 5x + 20 < 75

Subtract 20 both side,

⇒ 5x + 20 - 20 < 75 - 20

⇒ 5x < 55

⇒ 5x - 55 < 0

⇒ 5 (x - 11) < 0

⇒ x - 11 < 0

⇒ x < 11

Therefore, The required solution of inequality is,

⇒ x < 11

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What is another way to write 2×5 without using the multiplication sign?

Answers

Answer:

see below

Step-by-step explanation:

You could write it as 2+2+2+2+2 or 5+5 bc multiplication is like repeated addition.

Answer:

You can use the repeated additional as given below.

Step-by-step explanation:

2+2+2+2+2 or 5+5

A textile manufacturer has historically found an average of 0.1 flaws per square meter of cloth. Let X be the number of flaws in a bolt of 2000 square meters of cloth. How is X distributed

Answers

Answer:

Poisson distribution

Step-by-step explanation:

Given that :

There is an average of 0.1 flaws per square meter of cloth

So X = the number of flaws in a bolt of 2000 square meters of cloth.

The objective is to deduce how is X distributed.

Well, we can say X undergoes Poisson distribution.

Because, the flaw can be randomly positioned on the cloth and also dictate  how many times the event is likely to occur within a specified period of time.

Most time Poisson distribution is majorly used for independent events.

An independent is an event which contains two types of events occuring at a time say event [tex]E_1[/tex] and event [tex]E_2[/tex] and the event [tex]E_1[/tex] does not in any way affects the occurrence of the event [tex]E_2[/tex] .

Problem PageQuestion The mass of a radioactive substance follows a continuous exponential decay model, with a decay rate parameter of per day. Find the half-life of this substance (that is, the time it takes for one-half the original amount in a given sample of this substance to decay).

Answers

Answer:

8.55 days for a decay rate parameter of 8.1% per day

Step-by-step explanation:

Assuming a decay rate parameter of  8.1% per day

the general equation for radioactive decay is;

N = N₀e^(-λt)

x - decay constant (λ) - rate of decay 

t-  time 

N - amount remaining after t days , since we are calculating the half life, amount of time it takes for the substance to to be half its original value, its N₀/2

N₀ - amount initially present 

substituting the values 

N₀/2 = N₀e^(-0.081t)

0.5 = e^(-0.081t)

ln (0.5) = -0.081t

-0.693 = -0.081t

t = 0.693 / 0.081  = 8.55

half life of substance is 8.55 days 

What is the answer to x>-8

Answers

Answer:

Sorry, I cant understand rewrite it again.

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