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bixtya [17]
3 years ago
14

A researcher posts a newspaper advertisement offering $20 in exchange for participation in a short study. The researcher accepts

the first five people who respond to the advertisement. Which of the following statements is true about the sample? (5 points) a It is not a valid sample because it is only a short study. b It is a valid sample because money was offered to participants. c It is a valid sample because the first five people were selected to participate. d It is not a valid sample because it is not a random sample of the population.
Mathematics
2 answers:
xxTIMURxx [149]3 years ago
8 0
The Answer is C

Step by step Explenantion-

Alborosie3 years ago
5 0

Answer:

C : VALID

Step-by-step explanation:

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the coordinates of the vertex of a parabola in the xy-plane are (-4,k). If the y-intercept of the parabola is 12 and the parabol
svp [43]

The value of k is (A) 20/3.

<h3>What is a parabola?</h3>
  • A parabola is a planar curve that is mirror-symmetrical and roughly U-shaped in mathematics.
  • It fits various seemingly disparate mathematical descriptions, all of which can be shown to define the same curves.
  • A point and a line are two ways to describe a parabola.

To find the value of k:

  • y - b = c (x - a)²

Where (a, b) is the vertex and c is the constant.

  • (a, b) = (-4, k)
  • y - k = c (x - (- 4))²
  • y - k = c (x + 4)²

So,

  • x = 0, y = 12
  • 12 - k = 16c
  • k = 12 - 16c  ...... (1)

Then,

  • (-3, 7) = (x, y)
  • 7 - k = c (1)²
  • k = 7 - c  ...... (2)

Now,

  • 12 - 16c = 7 - c
  • 12 - 7 = 16c - c
  • 5 = 15c
  • c = 5/15 = 1/3

So, the value of k:

  • k = 12 - 16 (1/3) = 12 - 16/3 = 36-16/3 = 20/3

Therefore, the value of k is (A) 20/3.

Know more about a parabola here:

brainly.com/question/4061870

#SPJ4

The complete question is given below:

The coordinates of the vertex of a parabola in the XY plane are (-4,k). If the y-intercept of the parabola is 12 and the parabola passes through the point (-3,7), then what is the value of k?

(A) 20/3

(B) 16/5

(C) 14/3

(D) 12/5

5 0
2 years ago
-2(n+1)=6<br> n=<br> please help
densk [106]

-2(n + 1) = 6

Distribute the -2:

-2n -2 = 6

Add 2 to both sides:

-2n = 8

Divide both sides by-2

N = -4

8 0
3 years ago
A​ half-century ago, the mean height of women in a particular country in their 20s was inches. Assume that the heights of​ today
nadya68 [22]

Answer:

0.26684

Step-by-step explanation:

Given that :

Mean, μ = 62.5

Standard deviation, σ = 1.96

P(Z ≥ 63.72)

The Zscore = (x - μ) / σ

P(Z ≥ (x - μ) / σ)

P(Z ≥ (63.72 - 62.5) / 1. 96) = P(Z ≥ 0.6224)

P(Z ≥ 0.6224) = 1 - P(Z < 0.6224)

1 - P(Z < 0.6224) = 1 - 0.73316 = 0.26684

4 0
3 years ago
The average spending at Neco's salad bar is $9.03 with a standard deviation of $3.26. The distribution follows t-distribution. T
arlik [135]

Answer:

The difference between these cut-offs is of $1.9.

Step-by-step explanation:

In this question, we have to find the 90% confidence interval, using the t-distribution.

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 = 41 - 1 = 40

90% confidence interval

Now, we have to find a value of T, which is found looking at the t table, with 40 degrees of freedom(y-axis) and a confidence level of 1 - \frac{1 - 0.9}{2} = 0.95. So we have T = 1.684

The margin of error is:

M = T\frac{s}{\sqrt{n}} = 1.684\frac{3.26}{\sqrt{41}} = 0.95

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 9.03 - 0.95 = $8.08.

The upper end of the interval is the sample mean added to M. So it is 9.03 + 0.95 = $9.98.

What will be the difference between the upper and lower spending cut-offs which define the middle 90% of the customers if the sample contains 41 customers

$9.98 - $8.08 = $1.9

The difference between these cut-offs is of $1.9.

8 0
3 years ago
8 cm
djyliett [7]

Answer:

Step-by-step explanation:

A = (3.14)(8)2

= 200.96

3 0
3 years ago
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