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Readme [11.4K]
2 years ago
9

The Environmental Protection Agency (EPA) publishes fuel economy values that are known to be good estimates of the fuel economy

a typical driver will achieve under average driving conditions. One of the fuel economy values the EPA publishes is a combined estimate, which represents a combination of city driving (55%) and highway driving (45%). A large car rental company has 16 Ford Explorers in their fleet. They collected fuel economy data from these cars and calculated the sample mean to be 23.29 mpg and sample standard deviation as 0.78 mpg.
Required:
The car rental company is willing to assume that the conditions are met for constructing a confidence interval. Use the collected data to construct a 90% confidence interval for the mean combined fuel economy for Ford Explorers.
Mathematics
1 answer:
r-ruslan [8.4K]2 years ago
7 0

Answer:

The 90% confidence interval for the mean combined fuel economy for Ford Explorers is between 22.95 and 23.63 mpg.

Step-by-step explanation:

We have the standard deviation for the sample, which means that the t-distribution is used to solve this question.

The first step to solve this problem is finding how many degrees of freedom, we have. This is the sample size subtracted by 1. So

df = 16 - 1 = 15

90% confidence interval

Now, we have to find a value of T, which is found looking at the t table, with 15 degrees of freedom(y-axis) and a confidence level of 1 - \frac{1 - 0.9}{2} = 0.95. So we have T = 1.7531

The margin of error is:

M = T\frac{s}{\sqrt{n}} = 1.7531\frac{0.78}{\sqrt{16}} = 0.34

In which s is the standard deviation of the sample and n is the size of the sample.

The lower end of the interval is the sample mean subtracted by M. So it is 23.29 - 0.34 = 22.95 mpg

The upper end of the interval is the sample mean added to M. So it is 23.29 + 0.34 = 23.63 mpg

The 90% confidence interval for the mean combined fuel economy for Ford Explorers is between 22.95 and 23.63 mpg.

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Answer:

r = 2.23

Step-by-step explanation:

Use the formula:

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Solve for r:

r = C /2π = 14 /2·π = 2.228

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3 years ago
Find a fraction or mixed number that is between the two numbers -3/4 -1/3
Mandarinka [93]

Hey there!


-3/4 - 1/3

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≈ -9/12 - 4/12

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Therefore, your answer is/

-13/12 or -1 1/12

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6 0
2 years ago
Emilio and friends are in a submarine 500 feet below sea level. They continue to dive 35 feet each hour for 7 hours.
katovenus [111]
You would write the equation out as x=35x+500

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4 0
2 years ago
Set up a linear system and solve.
Karo-lina-s [1.5K]

Answer: The smaller integer is 12, while larger integer is 23

Step-by-step explanation:

The sum of two positive integer;

a + b = 35, when smaller integer is subtracted from twice the larger integer we have, 2a - b = 34 assuming b as the smaller integer, so your equation goes this way.

a + b = 35........(1)

2a - b = 34.......(2). To solve by elimination method add both equation. We have;

3a + 0 = 69

3a = 69, divide both sides by 3.

3a/3 = 69/3 so we have;

a = 23

To know the value of b, substitute 23 for the value of a in any of the equations, let's go with (1). From one we have;

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23 + b = 35

b = 35 - 23

b = 12.

Check: a + b = 35

23 + 12 = 35

35 = 35

The answer is correct.

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3 years ago
Which ordered pair is a solution of the equation?
ANEK [815]
I think it’s b I am sure
7 0
2 years ago
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