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Dmitriy789 [7]
2 years ago
14

A medical researcher studies the correlation between the number of hours spent at office jobs and the incidence of chronic back

ache. Which statement BEST describes why the investigation is an observational study?
A) The researcher does not use a control group.
B) The researcher does not intervene to vary conditions.
C) It is not possible to obtain a random sample of office workers.
D) It is not possible to establish a cause-effect relation between the variables.
Mathematics
1 answer:
Sati [7]2 years ago
5 0
The answer for this question is C 

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Suppose that receiving stations​ X, Y, and Z are located on a coordinate plane at the points ​(6​,2​), ​(negative 2​,negative 4​
marin [14]

Answer:

  (2,-1)

Step-by-step explanation:

A graph is useful here. Points X and Y have coordinate differences of ...

  X -Y = (6, 2) -(-2, -4) = (6+2, 2+4) = (8, 6)

Then the distance between X and Y is ...

  d = √(8² +6²) = √100 = 10

The point 5 units from X and from Y is the midpoint of XY:

  E = (X +Y)/2 = ((6, 2) +(-2, -4))/2 = (4, -2)/2 = (2, -1)

The epicenter is (2, -1).

_____

The graph shows circles of radius 5 around X and Y, and a circle of radius 13 around Z. The circles intersect at the point (2, -1), the epicenter.

5 0
2 years ago
A garden has a circular border and a fountain in the center. I measured the distance from one side of the garden to the other, g
Snezhnost [94]

Answer:

The length of the border is approximately 4 feet.

Step-by-step explanation:

Since the garden has a circular border we can apply the formula for the circle's length, which is shown below:

length = 2*\pi*radius

Where the radius is half the diameter. The diameter is the distance between two points in the circle going through the center, therefore for this garden the diameter is 1.2 feet and the radius is 0.6 feet. Applying this to the formula gives us:

length = 2*\pi*0.6\\length = 1.2*\pi\\length = 3.8

The length of the border is approximately 4 feet.

7 0
3 years ago
Which expression is equivalent to the following complex fraction?<br>1-1/x/2<br>​
pishuonlain [190]

<em>Look</em><em> </em><em>at</em><em> </em><em>the</em><em> </em><em>att</em><em>ached</em><em> </em><em>picture</em>

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7 0
3 years ago
Read 2 more answers
Please help me answer!!!!
yulyashka [42]

Answer:

C

Step-by-step explanation:

It can be any combination from 2/3/5/8

7 0
2 years ago
Read 2 more answers
Factor the polynomial
arlik [135]

Answer:

(5x+12) (5x-12)

Step-by-step explanation:

Use the difference of squares fromula. a^{2} -b^{2} =(a+b)(a-b)

Where a = 5x and b =12.

4 0
2 years ago
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