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Dmitriy789 [7]
3 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]3 years ago
5 0
The answer for this question is C 

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scoundrel [369]

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60

Step-by-step explanation:

Cot is the same as 1/tan so:

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7 0
3 years ago
another rectangle has length and width in the ratio of 3:2. If the length is increased by eight and the width is increased by 50
Andreyy89

Answer:

Area of the new rectangle  = 148.8 cm square

Step-by-step explanation:

Let x be the dimensions of the rectangle then the

Perimeter of the Original rectangle= 2(L+B)

                                                   = 2 ( 3x+2x) = 2(5x)= 10xcm

If the length is increased by eight the new length would be 3x+ 8

and width would be 2x+x= 3x after 50 % increase

Perimeter of the new rectangle= 2(L+B)

                                                     = 2 ( 3x+8 +3x)

                                                       = 2 (6x+8)

                                                       = 12x + 16

Ratio of the new perimeter to the original perimeter is

             New perimeter :   Original perimeter

                8                      : 5

           12x+ 16                   : 10x cm

80x= 60x + 16

20x= 16

x= 16/20= 4/5

Putting the value of length and breadth in place of x

Area of the new rectangle = L*B =  3 * (4/5) +8 *3(4/5)=

                                                                 = 12+ 40/5 * 12/5

                                                                   = 62/5* 12/5

                                                                     = 744/5

                                                                   = 148.8 cm square

8 0
3 years ago
If x^2=y^2+z^2<br><br> what does x equal?
Zepler [3.9K]

Answer:

\displaystyle x = \sqrt{y^2 + z^2}

General Formulas and Concepts:

<u>Pre-Algebra</u>

  • Equality Property

<u>Algebra i</u>

  • Terms/Coefficients

Step-by-step explanation:

<u>Step 1: Define</u>

<em>Identify</em>

\displaystyle x^2 = y^2 + z^2

<u>Step 2: Solve for </u><em><u>x</u></em>

  1. [Equality Property] Square root both sides:                                                    \displaystyle x = \sqrt{y^2 + z^2}
3 0
3 years ago
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