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nekit [7.7K]
3 years ago
7

You are conducting a study on the health of people who have been exposed to radiation and those who have not been exposed to rad

iation. Which of these methods of obtaining data should you most likely adopt and why?
a. an observational study because it involves the pre-existing condition of the subjects
b. an experimental study because it will give the most accurate results
c. an experimental study because results can be obtained much faster using this technique
d. a sample survey with only people who were not exposed to radiation because it involves random selection
e. a sample survey with only people who were exposed to radiation because it involves random selection
Mathematics
2 answers:
coldgirl [10]3 years ago
8 0

Answer:

a. an observational study because it involves the pre-existing condition of the subjects

Step-by-step explanation:

Given that You are conducting a study on the health of people who have been exposed to radiation and those who have not been exposed to radiation.

Already some people exposed to radiation and not exposed is being taken for sample.

Hence here no change is made so it is only an observational study and not experimental study.

Option e, d are incorrect sinc both groups must be observed.

Option b and c are incorrect because this is not an experimental study.

Hence correct option is

a. an observational study because it involves the pre-existing condition of the subjects

nadya68 [22]3 years ago
5 0
Thank you for posting your question here at brainly. Feel free to ask more questions.   
<span>
The best and most correct answer among the choices provided by the question is </span><span>a. an observational study because it involves the pre-existing condition of the subjects</span>.    
      <span>
Hope my answer would be a great help for you.  </span>
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Reduce 12/20 to lowest term
skelet666 [1.2K]

Answer:

3/5

Step-by-step explanation:

12/20

(divide both by 2)

12/2= 6

20/2=10

6/10

(divide by both by 2)

6/2= 3

10/2= 5

3/5

7 0
3 years ago
A rectangle has the following vertices. Find the area of the rectangle. (9, −1), (−1, 7), (−5, 2), (5, −6)
stiks02 [169]

Answer:  82 sq. units .

Step-by-step explanation:

Let A (9, −1), B (−1, 7), C(−5, 2), D(5, −6) are the vertices of rectangle.

Then we plot them on graph ( as provided in attachment)

Length = AB =\sqrt{(9+1)^2+(-1-7)^2} units  [By distance formula : \sqrt{(x_2-x_1)^2+(y_2-y_1)^2}]

=\sqrt{(10)^2+(-8)^2}=\sqrt{100+64}=\sqrt{164}=2\sqrt{41} units

Width = BC = \sqrt{(-1+5)^2+(7-2)^2} units

=\sqrt{4^2+5^2}\\\\=\sqrt{16+25}\\\\=\sqrt{41}

Area = length x width

= 2\sqrt{41}\times\sqrt{41}=2\times41= 82\text{ sq. units}

Hence, the  area of the rectangle is 82 sq. units .

7 0
3 years ago
a student walks 50m on a bearing 0.25 degrees and then 200m due east how far is she from her starting point.​
Inessa05 [86]

Answer:

Step-by-step explanation:

I'm going to use Physics here for this concept of vectors. Here are some stipulations I have set for the problem (aka rules I set and then followed throughout the problem):

** I am counting the 50 m as 2 significant digits even though it is only 1, and I am counting 200 as 3 significant digits even though it is only 1. 1 sig dig doesn't really give us enough accuracy, in my opinion.

** A bearing of .25 degrees is measured from the North and goes clockwise; that means that measured from the x axis, the angle is 89.75 degrees. This is the angle that is used in place of the bearing of .25 degrees.

** Due east has an angle measure of 0 degrees

Now let's begin.

We need to find the x and y components of both of these vectors. I am going to call the first vector A and the second B, while the resultant vector will be C. Starting with the x components of A and B:

A_x=50cos(89.75) so

A_x=.22

B_x=200cos(0) so

B_x=200 and we need to add those results together. Due to the rules for adding significant digits properly, the answer is

C_x=200 (and remember I am counting that as 3 sig fig's even though it's only 1).

Now for the y components:

A_y=50sin(89.75) so

A_y=50 (which I'm counting as 2 sig fig's)

B_y=200sin(0) so

B_y=0 and we need to add those results together.

C_y=50

Now for the resultant magnitude:

C_{mag}=\sqrt{(200)^2+(50)^2}  and that gives us a final magnitude of

C_{mag}=206 m

Now for the angle:

Since both the x and y components of the resultant vector are in quadrant 1, we don't need to add anything to the angle to get it right, so

tan^{-1}(\frac{50}{200})=14

The girl is 206 meters from her starting point at an angle of 14 degrees

4 0
3 years ago
Please need help with this question m
katovenus [111]

Answer:

D.

Step-by-step explanation:

3(5)+2 > 14= 17>14 which is true

10-5 less than or equal to 7

true, 5 is less than 7

7 0
3 years ago
Read 2 more answers
What is the missing constant term in the perfect square that starts with x^2-12x
Ipatiy [6.2K]

Essentially, we are trying to find the missing constant term of (x - a)^2 (remember that we are subtracting a due to the negative sign in front of the second term). Let's expand this to see what we can work with:

(x - a)^2

  • Set up

x^2 - ax - ax + a^2 = x^2 - 2ax + a^2

  • FOIL and simplify

Now, we know the second term is 12x, so let's set the second term in the polynomial we just found equal to 12x:

2ax = 12x

  • Set up

2a = 12

  • Divide both sides of the equation by x

a = 6

  • Divide both sides of the equation by 2

We have found a = 6. We know the missing constant term is a^2, according to the polynomial we found earlier. Thus, the missing term is:

a^2 \Rightarrow 6^2 = 36


The missing constant term is 36.

4 0
3 years ago
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