For each of the studies described, explain whether the study was an observational study or a randomized experiment.
a. A group of 100 students was randomly divided, with 50 assigned to receive vitamin C and the remaining 50 to receive a placebo, to determine whether or not vitamin C helps to prevent colds.
b. A random sample of patients who received a hip transplant operation at Stanford University Hospital during 2000 to 2010 will be followed for 10 years after their operation to determine the success (or failure) of the transplant.
c. Volunteers with high blood pressure were randomly divided into two groups. One group was taught to practice meditation and the other group was given a low-fat diet. After 8 weeks, reduction in blood pressure was compared for the two groups.

Answers

Answer 1

Answer:

B

Step-by-step explanation:

B


Related Questions

What proportion of families own as opposed to rent their home? To find out, an urban planner selected a random
sample of 400 families in a large city to participate in a survey about homeownership. Of the 362 families that
responded to the survey, 42% reported that they own their home. Which of the following statements about the
survey results is true?
O A suitable estimate of all families who own their home is 42%.
The survey suffers from voluntary response bias and may not accurately represent the population.
O Only 362 responses cannot provide a suitable estimate of families who own their home.
O The survey suffers from undercoverage and may not provide a suitable estimate of homeownership.
Mark this and return
Save and Exit
fyext
Submit

Answers

Answer:

A suitable estimate of all families who own their home is 42%.

Step-by-step explanation:

42% reported that they own their home.

This means that the sample proportion is of 42%. So that an estimate for the percentage of all families who own their home is of 42%., and that the first option is correct.

Answer:

The correct answer is: The survey suffers from undercoverage and may not provide a suitable estimate of homeownership.

Step-by-step explanation:

I just took the review test. The person above me is wrong

What is the domain of the square root function graphed below?

Answers

Answer:

Set the expression inside the square root greater than or equal to zero. We do this because only nonnegative numbers have a real square root, in other words, we can not take the square root of a negative number and get a real number, which means we have to use numbers that are greater than or equal to zero.

Step 2: Solve the equation found in step 1. Remember that when you are solving equations involving inequalities, if you multiply or divide by a negative number, you must reverse the direction of the inequality symbol.

Step 3: Write the answer using interval notation.

Determine whether carpeted rooms have more bacteria than uncarpeted rooms at the level of significance. Normal probability plots indicate that the data are approximately normal and boxplots indicate that there are no outliers.

Carpeted Un-Carpeted
15.9 8.1 15 7.2 10.4 6.1
11.2 16 11.2 6.8 11.3 6.8
8.6 10 12.1 6.3

Requried:
State the null and alternative hypotheses. Let population 1 be carpeted rooms and population 2 be uncarpeted rooms.

Answers

Answer:

The null (H[tex]_{0}[/tex]) and alternative (H[tex]_{1}[/tex]) hypotheses can be stated as follows:

H[tex]_{0}[/tex]:  μ[tex]_{1}[/tex] = μ[tex]_{2}[/tex].

H[tex]_{1}[/tex]: μ[tex]_{1}[/tex] > μ[tex]_{2}[/tex].

Step-by-step explanation:

In the question, the given assertion is that carpeted rooms have more bacteria than uncarpeted rooms, i.e. μ[tex]_{1}[/tex] > μ[tex]_{2}[/tex].

The assertion made in the question can either be the null hypothesis (H[tex]_{0}[/tex]) or the alternate hypothesis (H[tex]_{1}[/tex]). An equality must be present in the null hypothesis. The alternative hypothesis expresses the exact opposite of the null hypothesis if the claim is the null hypothesis.

Therefore, the null (H[tex]_{0}[/tex]) and alternative (H[tex]_{1}[/tex]) hypotheses can be stated as follows:

H[tex]_{0}[/tex]:  μ[tex]_{1}[/tex] = μ[tex]_{2}[/tex].

H[tex]_{1}[/tex]: μ[tex]_{1}[/tex] > μ[tex]_{2}[/tex].

which equation is correctly rewritten to solve for x?

Answers

i think it’s lxwxh i’m not sure sorry if it didn’t help
explanation

5+9+9 divided by 3= ?

Answers

It’s 7.7 because you round it the the nearest ten which is 6 turns into a 7 by adding one

Two angles are complementary. One angle measures 60 degrees. What is the measure of the other angle?
I'm not sure if its A.

Answers

Answer:

30

Step-by-step explanation:

Complementary angles add to 90

x+60 = 90

x+60-60 = 90-60

x = 30

Answer: A

Step-by-step explanation:

Complementary angles sum up to 90 degrees. Thus, we can write that:

90=angle1+angle2

90-angle1=angle2

90-60=angle2

angle2=30

Find the area of the figure below (Do Not put the units in your answer)

Answers

Answer:

54

Step-by-step explanation:

Area of rhombus= (12×9) ÷2

Which statement describes the sequence defined by a Subscript n Baseline = StartFraction n cubed minus n Over n squared + 5 n EndFraction?

Answers

Answer:

The answer is " The sequence converges to infinity. "

Step-by-step explanation:

Given:

[tex]\to a_n=\frac{n^3-n}{n^2+5n}[/tex]

[tex]\lim_{n \to \infty} a_n= \lim_{n \to \infty} \frac{n^3-n}{n^2+5n}[/tex]

                   [tex]= \lim_{n \to \infty} \frac{n(n^2-1)}{n(n+5)}\\\\= \lim_{n \to \infty} \frac{(n^2-1)}{(n+5)}\\\\= \lim_{n \to \infty} \frac{n(n-\frac{1}{n})}{n(1+\frac{5}{n})}\\\\= \lim_{n \to \infty} \frac{(n-\frac{1}{n})}{(1+\frac{5}{n})}\\\\[/tex]

Denominator[tex]= \lim_{n \to \infty} 1+\frac{5}{n}=1+\lim_{n\to \infty} \frac{5}{n}=1+0=1[/tex]

Numerator [tex]=\lim_{n\to \infty}n-\frac{1}{n}=\infty[/tex]

[tex]\therefore\\\\\lim_{n\to \infty}a_n=\frac{\infty}{1} =\infty[/tex]

Eric wants to buy a new hat
which costs $17. He made
$5 by raking leaves and
$8 by washing cars.
How much more money does he need?

Answers

Answer:

the answer is 4

Step-by-step explanation:

you subtract 13 from 17 =4

for what value of x does 4x=(1/8)^x+6?
Answer please help
A. -15
B. -3
C. 3
D. 15

Answers

Im sorry but what I got was x=1.5 I don't know if this helps or not.

given the function f(x) = 2x^2 - 6x +4. calculate the following values

Answers

Answer:

x^1 = 1, x^2 =2

Step-by-step explanation:

its hard to explain but there's the answer

what type of data states that every value in the set is a number​

Answers

Answer:

QUALITATIVE DATA-type of data states that every value in the set is a number.

Step-by-step explanation:

QUALITATIVE DATA-type of data states that every value in the set is a number.

Answer:

QUALITATIVE DATA-type of data states that every value in the set is a number.

You put $600 in a savings account. The account earns 6% simple interest per year.

a. What is the interest earned after 10 years?
b. What is the balance after 10 years?

Answers

A I believe hope this helps

Consider a fishery in which harvesting is taking placeat a constant rateh. The population at the fisherywill be modeled by

dP/dt = kP- h

Required:
Find the general solution to this DE.

Answers

Answer:

The general solution to this differential equation is [tex]P(t) = \frac{Ke^{kt} + h}{k}[/tex]

Step-by-step explanation:

We are given the following differential equation:

[tex]\frac{dP}{dt} = kP - h[/tex]

Solving by separation of variables:

[tex]\frac{dP}{kP-h} = dt[/tex]

Integrating both sides:

[tex]\int \frac{dP}{kP-h} = \int dt[/tex]

On the left side, by substitution, u = kP - h, du = kDp, Dp = du/k. Then

[tex]\frac{1}{k} \ln{kP-h} = t + K[/tex]

In which K is the constant of integration.

[tex]\ln{kP-h} = kt + K[/tex]

[tex]e^{\ln{kP-h}} = e^{kt + K}[/tex]

[tex]kP - h = Ke^{kt}[/tex]

[tex]kP = Ke^{kt} + h[/tex]

[tex]P(t) = \frac{Ke^{kt} + h}{k}[/tex]

The general solution to this differential equation is [tex]P(t) = \frac{Ke^{kt} + h}{k}[/tex]

Gemma, a scuba diver, begins a dive on the side of a boat 4 feet above sea level. She descends 28 feet. Which integer represents Gemma’s position with respect to sea level?
–32

Answers

Answer:

-24 feet

Step-by-step explanation:

Boat is 4 feet above sea level => +4 feet

She descends 28 feet => -28 feet

Position = +4-28 = -24 feet

Therefore,

Gemma is 24 feet below the sea level

Answer:

-24 feet

Step-by-step explanation:

Because she is 4 feet above sea level, she can descend 4 feet to be at sea level. Now she only has to descend 24 feet below sea level, which is -24 feet.

Complete the function, count_bases(s). It takes as input a DNA sequence as a string, s. It should compute the number of occurrences of each base (i.e., 'A', 'C', 'G', and 'T') in s. It should then return these counts in a dictionary whose keys are the bases.

Answers

Answer:

The function is as follows:

def count_bases(DNA_str):

   retDNA = {}

   for i in DNA_str:

       if i in retDNA:

           retDNA[i]+=1

       else:

           retDNA[i] = 1

   return retDNA

Step-by-step explanation:

This defines the function

def count_bases(DNA_str):

This initializes a dictionary

   retDNA = {}

This iterates through the dictionary

   for i in DNA_str:

If an item exists in the dictionary

       if i in retDNA:

The count is updated by 1

           retDNA[i]+=1

Otherwise

       else:

The count is set to 1

           retDNA[i] = 1

This returns the DAN

   return retDNA

As preparation for designing a new line of business wear, a clothing manufacturer asked a large sample of department store customers, "What is your favorite
color of dress shirt?" The ple chart below summarizes their responses.
(a) Which color was chosen by approximately one fourth of
the customers?

Answers

Answer:

white

Step-by-step explanation:

if you cut the shape in half both ways it makes white take up a fourth.


Learning Task 1: Conduct a survey of the favorite fruit of your classmates and/or friends 10 boys and 10 girls by
sending them messages on messenger or SMS. Use the table to record the data.
Favorite Fruit of My Classmate and Friends
Tally
Fruits
Boys
Girls
1. pineapples
2. ripe mangoes
3. rambutan
4. lansones
5. buko
Answer the following questions:
1. What is the set of data all about?
2. Which fruit is the favorite among the girls Boys
3. What is the least favorite fruit among the girls Boys
4. What is the top choice fruit of both girls and boys
5. What is the least favorite fruit of both boys and girls​

Answers

Answer:

1 Its all about there favorite fruits

2 the favorite fruits of the girls are buko less than the boys.

3 the least fruit favorite fruits is pineapple among the girls boys.

4 the top choice of the fruit is the lansones both girls and boys.

5 the rambutan is the least favorite both of them

Step-by-step explanation:

Hope its help po pa brainlest

Answer:

girl

-apple

-masanas

boy

-lansones

-rambotan

sorry yan lang alam ko

if the volume of a Sphere is 36 pie cm³. then find its radius
I will give brainliest ​

Answers

Answer: r = 3

Step-by-step explanation:

V=(4/3)πr^3 (this is the formula to identify a volume of the sphere. Since we know that V = 36π, add it into the following formula like so:

36π = (4/3)πr^3; from here we can cancel out the π

36 = (4/3)r^3; multiply both sides by 3/4

27 = r^3;

the final answer is r = 3.


If point (x, y) is rotated 90 degrees about the origin, the resulting point is (-y, -x).
True or false?

Answers

Answer:

False

Step-by-step explanation:

Take the point (2, 3)  = (x, y)

Rotated 90º clockwise (3, -2) = (y, -x)

Rotated 90º counter clockwise (-3, 2) = (-y, x)

Neither rotation becomes (-3, -2)

PLEASE HELP ASAP!!! What is the range of the function shown on the graph?
(The graph is below)

Answers

Answer:

-6 < y < ∞

Step-by-step explanation:

The range is the values that y can take

y goes from  almost -6 to infinity ( there is an asymptote at -6)

-6 < y < ∞

what is the area of a rectangular driveway measuring 20 feet long and 15 feet wide?

Answers

Answer:

300 square feet

Step-by-step explanation:

Area is found by multiplying the length and width of a surface

Which of the following best describes the equation below? y = x + 8 OA. function only B. both a relation and a function Oc. neither a relation nor a function OD. relation only?​

Answers

9514 1404 393

Answer:

  B. both a relation and a function

Step-by-step explanation:

Every linear equation with defined slope is both a relation and a function.

__

Only a vertical line of the form x=constant is linear equation that is a relation, but not a function.

the temperature at 6 pm in frost frozen antarctica was -37 if the tem dropped 8 1 /2 c uring the next hour what was the the temp at 7 pm

Answers

Answer:

-45 1/2

Step-by-step explanation:

How many vertices does a triangular prism have?
4 5 6 9

Answers

Answer:

6

Step-by-step explanation:

Answer:

6

Step-by-step explanation:

Vertices are the vertex points. there are 4 vertices at the bottom and 2 vertices at the top which makes 6.

Hope this helps

The points P and Q have coordinates (-1, 6) and (9, 0) respectively.
The line l is perpendicular to PQ and passes through the mid-point of PQ.
Find an equation for l, giving your answer in the form ax + by + c =0, where a, b and c are integers.

Answers

Answer:

[tex]3y - 5x +11=0[/tex]

Step-by-step explanation:

Given

[tex]P(x_1,y_1) = (-1,6)[/tex]

[tex]Q(x_2,y_2) = (9,0)[/tex]

Required

The equation of l

First, calculate the slope (m) of PQ

[tex]m = \frac{y_2 - y_1}{x_2 - x_1}[/tex]

[tex]m = \frac{0-6}{9--1}[/tex]

[tex]m = \frac{-6}{10}[/tex]

[tex]m = \frac{-3}{5}[/tex]

Since l is perpendicular to PQ, the slope of l is:

[tex]m_2 = -\frac{1}{m}[/tex]

[tex]m_2= -\frac{1}{-3/5}[/tex]

[tex]m_2 = \frac{5}{3}[/tex]

Next, calculate the midpoint of PQ

[tex]M = \frac{1}{2}(x_1 + x_2,y_1+y_2)[/tex]

[tex]M = \frac{1}{2}(-1+9,6+0)[/tex]

[tex]M = \frac{1}{2}(8,6)[/tex]

[tex]M = (4,3)[/tex]

The equation of l is:

[tex]y = m(x -x_1) + y_1[/tex]

[tex]y = \frac{5}{3}(x -4) +3[/tex]

Multiply through by 3

[tex]3y = 5(x -4) +9[/tex]

Open bracket

[tex]3y = 5x -20 +9[/tex]

[tex]3y = 5x -11[/tex]

Rewrite as:

[tex]3y - 5x +11=0[/tex]

The amount of increase from the cost to the selling price is called the?​

Answers

Answer:

profit

hope it is helpful to you

Step-by-step explanation:

Markup is the percentage amount by which the cost of a product is increased to arrive at the selling price.

Find the time required for an investment of 7,000 dollars to grow to 14,000 dollars at an interest rate of 4% per
year, compounded monthly. Give your answer accurate to 2 decimal places.
Preview
years.

Answers

Answer:

The time required is of 17.53 years.

Step-by-step explanation:

Compound interest:

The compound interest formula is given by:

[tex]A(t) = P(1 + \frac{r}{n})^{nt}[/tex]

Where A(t) is the amount of money after t years, P is the principal(the initial sum of money), r is the interest rate(as a decimal value), n is the number of times that interest is compounded per year and t is the time in years for which the money is invested or borrowed.

Find the time required for an investment of 7,000 dollars to grow to 14,000 dollars at an interest rate of 4% per year, compounded monthly.

This is t for which [tex]A(t) = 14000[/tex], considering [tex]P = 7000, r = 0.04, n = 12[/tex]. So

[tex]A(t) = P(1 + \frac{r}{n})^{nt}[/tex]

[tex]14000 = 7000(1 + \frac{0.04}{12})^{12t}[/tex]

[tex](1.0033)^{12t} = 2[/tex]

[tex]\log{(1.0033)^{12t}} = \log{2}[/tex]

[tex]12t\log{1.0033} = \log{2}[/tex]

[tex]t = \frac{\log{2}}{12\log{1.0033}}[/tex]

[tex]t = 17.53[/tex]

The time required is of 17.53 years.

Solve the following system of equations and show all work. y = 2x2-3 y = 7x + 1 (10 points)​

Answers

Answer:

x = -1/2 , y = -5/2

x = 4, y = 29

Step-by-step explanation:

y = 2x² - 3

y = 7x + 1

------------------

set equal

2x² - 3 = 7x + 1

Subtract 7x + 1 from both sides

2x² - 7x - 4 = 0

Factor

(2x + 1)(x - 4) = 0

x = {-1/2, 4}

For x = -1/2

y = 7(-1/2) + 1

y = -5/2

(-1/2 , -5/2)

For x = 4

y = 7(4) + 1

y = 29

(4, 29)

ANSWER ASAPPP PLSSS. ILL MARK BRAINLIEST TOO



A scientist is studying the growth of a particular species of plant. He writes the following equation to show the height of the plant f(n), in cm, after n days:


f(n) = 10(1.02)n


Part A: When the scientist concluded his study, the height of the plant was approximately 11.04 cm. What is a reasonable domain to plot the growth function? (4 points)


Part B: What does the y-intercept of the graph of the function f(n) represent? (2 points)


Part C: What is the average rate of change of the function f(n) from n = 1 to n = 5, and what does it represent? (4 points)

Answers

Answer:

Step-by-step explanation:

11.04 = 10(1.02)^n

1.104 = 1.02^n

ln 1.104 = ln 1.02^n

ln 1.104 = n ln 1.02

n = ln 1.104/ ln 1.02

n = 4.99630409516

4.99 can be rounded to 5.

So a reasonable domain would be 0 ≤ x < 5

PART B)

f(0) = 10(1.02)^0

f(0) = 10(1)

f(0) = 10

The y-intercept represents the height of the plant when they began the experiment.

f(1) = 10(1.02)^1

f(1) = 10(1.02)

f(1) = 10.2

(1, 10.2)

f(5) = 10(1.02)^5

f(5) = 10(1.1040808)

f(5) = 11.040808

f(1)=10(1.02)^1

f(1)=10.2

Average rate= (fn2-fn1)/(n2-n1)

                     =11.04-10.2/(5-1)

                    =0.22

the average rate of change of the function f(n) from n = 1 to n = 5 is 0.22.  

Answer:

Part A

The domain should be 0 ≤n≤5

Part B

f(n) = 10(1.02)^n

The function is in the form y =a b^x  where a is the y intercept

The y intercept is 10.  This is the value when n =0 days.

Part C

The average rate of growth over the 4 days is .21 cm per day

Step-by-step explanation:

f(n) = 10(1.02)^n

Part A

Let f(n) = 11.04

11.04 = 10 * 1.02 ^n

Divide each side by 10

11.04/10 = 1.02^n

1.104 = 1.02^n

Taking the log of each side

log 1.104 = log 1.02^n

We know log a^b = b log a

log 1.104 = n log 1.02

log 1.104 / log 1.02 = n

4.99630=n

Rounding n to 5

The domain should be 0 ≤n≤5

Part B

f(n) = 10(1.02)^n

The function is in the form y =a b^x  where a is the y intercept

The y intercept is 10.  This is the value when n =0 days.

Part C

To find the average rate of change

f(5) - f(1)

-----------

5-1

f(5) = 11.04  

f(1) = 10 *1.02 =10.2

11.04 - 10.2

-----------

5-1

.84

-----

4

.21 cm per day

The average rate of growth over the 4 days is .21 cm per day

Other Questions
1.who is the frist prime minister of India2.who is the first Indian to climb mount Everest3.who was the first woman prime minister of India4.who was the first Indian footballer5.who was the first Indian cricketer6.how many colours does Indian flag have?Name them7.what state is the head of india in india map8.who was the first Indian to go on moon9.who is the best scientist of India10.who invented 0 A corporation had the following assets and liabilities at the beginning and end of this year. Assets LiabilitiesBeginning of the year $57,000 $24,436 End of the year 115,000 46,575 a. Owner made no investments in the business, and no dividends were paid during the year. b. Owner made no investments in the business, but dividends were $1,250 cash per month. c. No dividends were paid during the year, but the owner did invest an additional $55,000 cash in exchange for common stock. d. Dividends were $1,250 cash per month, and the owner invested an additional $35,000 cash in exchange for common stock. Determine the net income earned or net loss incurred by the business during the year for each of the above separate cases: a.b.c.d.Beginning of the year Which of these sentences correctly uses coordinate adjectives? PLEASE HELP WITH THIS GEOMETRY PROJECT IM GIVING ALL MY POINTS (45) Write a pseudocode to calculate the factorial of a number how can discussions projects campaigns and events support victims of human trafficking ques mid vallue frequency5. 510. 2015. 1020. 5525. 2230. 29find mode from the following what is the defnition of endocytosis What is a Parrel line? 10-Concentration is the amount of a substance in a predefined volume of space. The basic measurement of concentration in chemistry is molarity or the number of moles of solute per liter of solvent. What is the molarity of a solution containing 9.478 grams of Rucl, in enough water to make 1.00 L of solution? y = -4/3x 1y = 1/3x + 4 which one is the smallest 4/5 1/6 2/3 1/5 How does adding the affix -etic to the words energy, athlete, and poet change the meanings of these words?It changes them from nouns to adjectives.It changes them from adjectives to nouns.It changes them from nouns to adverbs.It changes them from adverbs to nouns. In a republic, elected officials create laws to regulate the economy.F f(x) = 6r + 2g(x) = - 5x - 9Find the product of F and G. If property rights are not well enforced, all of the following are likely to occur except;_________ A. a significant number of people will be willing to risk their funds by investing them in local businesses. B. fewer goods and services will be produced C. economic efficiency will be reduced D. an economy will produce inside its production possibilities frontier. Thank yall for helping Read the passage from "The Tell-Tale Heart.I think it was his eye! yes, it was this! He had the eye of a vulturea pale blue eye, with a film over it. Whenever it fell upon me, my blood ran cold; and so by degreesvery graduallyI made up my mind to take the life of the old man, and thus rid myself of the eye forever. Now this is the point. You fancy me mad. Madmen know nothing. But you should have seen me. You should have seen how wisely I proceededwith what cautionwith what foresightwith what dissimulation I went to work! I was never kinder to the old man than during the whole week before I killed him.How is suspense created for the reader in this passage?The reader wonders where the old man lives.The reader is waiting to find out details of the murder.The reader envisions a vulture with pale blue eyes.The reader does not know why the old man is killed. In your opinion, what was the BEST part of the 2020-2021 school year? What made it the best? find the value of x in the given right triangle 90 20. please help!