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AfilCa [17]
2 years ago
10

The management of a large airline wants to estimate the average time after takeoff taken before the crew begins serving snacks a

nd beverages on their flights. Assuming that management has easy access to all of the information that would be required to select flights by each proposed method, which of the following would be reasonable methods of stratified sampling?
a. For each day of the week, randomly select 5% of all flights that depart on that day of the week.
b. Divide all flights into the following 4 groups on the basis of scheduled departure time: before 9:00 am 9:00 am to 1:00 pm. 1:00 pm to 5:00 pm, and after 5:00 pm. Randomly select 5% of the flights in each group.
c. For each crew member the airline employs, randomly select 5 flights that the crew member works.
d. Divide the airports from which the airline's fights depart into 4 regions: Northeast, Northwest Southwest and Southeast. Randomly select 5% of all flights departing from airports in each region
Mathematics
1 answer:
Dahasolnce [82]2 years ago
3 0

Answer:

The answer is "Option a, Option b, and Option d".

Step-by-step explanation:

In the given question it is used to stratifying the sampling if the population of this scenario it flights takes off when it is divided via some strata.

  • In option a, In this case, it stratified the sampling, as the population of planes taking off has been divided into the days of the week.
  • In option b, It also used as the case of stratified sampling.
  • In options c, it is systematic sampling, that's why it is wrong.
  • In option d,  It is an example of stratifying the sampling.
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Stella [2.4K]

For the given cost equation we have:

a) Fixed cost is $900.

b) For making 25 items the cost is $1150.

c) D: x ∈ [0, 150]

   R: c ∈ [900, 2400]

<h3>Working with the cost equation.</h3>

Here we know that the cost equation is:

c(x) = 10*x + 900.

First, we want to get the fixed cost, it is given by evaluating the function in x = 0.

c(0) = 10*0 + 900 = 900

The fixed cost is 900.

b) Now we want to get the cost for making 25 items, to get this, we just evaluate in x = 25.

c(25) = 10*25 + 900 = 250 + 900 = 1150

c) Now, if the maximum cost is 2400, then the maximum number of items that we can make is x₀, such that:

c( x₀) = 2400 = 10*x₀ + 900

Solving for x₀ we get:

x₀ = (2400 - 900)/10 = 150

Now we want to get the range and domain.

We know that we can make between 0 and 150 items, so the domain is:

D: x ∈ [0, 150]

For the range, we know that the fixed cost for 0 items is 900, and the maximum cost is 2400, then the range is:

R: c ∈ [900, 2400]

If you want to learn more about domain and range:

brainly.com/question/10197594

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Explanation:

Te standard form of the parabola is,

f(x)=a(x-h)^2+k        .....(1)

Where,  (h,k) is the vertex of the parabola.

(1)

The given equation is,

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To make perfect square add (\frac{b}{2a})^2, i.e., 9. Since there is factor 3 outside the parentheses, so subtract three times of 9.

f(x)=3(x^2-6x+9)+24-3\times 9

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f(x)=4x^2+8x+7

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y=x^2+4x+7

To make perfect square add (\frac{b}{2a})^2, i.e., 2^2.

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Use factoring method to find the factors of the equation.

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f(x)=3x(x-5)(x+1)

Equate each factor equal to 0.

x=0,-1,5

Therefore, the zeros of the given equation is 0, -1, 5 and the correct option is 2.

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