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OverLord2011 [107]
3 years ago
9

A group of scientists is conducting an experiment on the effects of media on children. They randomly select 100 children and ran

domly assign
each child to one of four treatment groups. Each treatment group has a specific amount of screen time during a one-week time frame. The
first group has no screen time, the second group has two hours of screen time, the third group has four hours of screen time, and the fourth
group has six hours of screen time,
After the first week, the scientists conduct the same experiment, with the same subject groups, for three more weeks so that each group
experiences each of the four treatments.
Which statements about this study are true?
This study uses blinding.
This study uses random sampling
This study uses a control group.
ооо
This study uses blocking.
This study uses a repeated measures design.
Mathematics
1 answer:
Marysya12 [62]3 years ago
8 0

The statements that are true about this study are:

  • This study uses random sampling.
  • This study uses a control group.
  • This study uses a repeated measures design. ​

Random sampling occurs when each sample has an equal probability of being chosen in a study.

This is seen in the random selection of 100 children. The Control group was used with the first group that had no screen time.

The repeated measures design was also used when multiple measurements were taken during different weeks.

Learn more about experiments here:

brainly.com/question/17216882

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The cone in the figure below has a volume of 722 cubic centimeters and a height of 6
azamat

Answer:

r = 10.72 cm

Step-by-step explanation:

h = 6 cm

Volume of cone = 722 cubic cm

\frac{1}{3}\pi r^{2}h=722\\\\\frac{1}{3}*3.14*r^{2}*6=722\\\\r^{2}=\frac{722*3}{3.14*6}\\\\r^{2}=114.97\\\\r = \sqrt{114.97}\\\\r = 10.72

4 0
3 years ago
Tim needs 23 3/4 m of wood trim to remodel a room. Wood trim is sold in lengths of 1 1/4 m. What equation can be used to find th
Bumek [7]
I hope this helps you

5 0
4 years ago
For 0 ≤ ϴ < 2π, how many solutions are there to tan(StartFraction theta Over 2 EndFraction) = sin(ϴ)? Note: Do not include va
Black_prince [1.1K]

Answer:

3 solutions:

\theta={0, \frac{\pi}{2}, \frac{3\pi}{2}}

Step-by-step explanation:

So, first of all, we need to figure the angles that cannot be included in our answers out. The only function in the equation that isn't defined for some angles is tan(\frac{\theta}{2}) so let's focus on that part of the equation first.

We know that:

tan(\frac{\theta}{2})=\frac{sin(\frac{\theta}{2})}{cos(\frac{\theta}{2})}

therefore:

cos(\frac{\theta}{2})\neq0

so we need to find the angles that will make the cos function equal to zero. So we get:

cos(\frac{\theta}{2})=0

\frac{\theta}{2}=cos^{-1}(0)

\frac{\theta}{2}=\frac{\pi}{2}+\pi n

or

\theta=\pi+2\pi n

we can now start plugging values in for n:

\theta=\pi+2\pi (0)=\pi

if we plugged any value greater than 0, we would end up with an angle that is greater than 2\pi so,  that's the only angle we cannot include in our answer set, so:

\theta\neq \pi

having said this, we can now start solving the equation:

tan(\frac{\theta}{2})=sin(\theta)

we can start solving this equation by using the half angle formula, such a formula tells us the following:

tan(\frac{\theta}{2})=\frac{1-cos(\theta)}{sin(\theta)}

so we can substitute it into our equation:

\frac{1-cos(\theta)}{sin(\theta)}=sin(\theta)

we can now multiply both sides of the equation by sin(\theta)

so we get:

1-cos(\theta)=sin^{2}(\theta)

we can use the pythagorean identity to rewrite sin^{2}(\theta) in terms of cos:

sin^{2}(\theta)=1-cos^{2}(\theta)

so we get:

1-cos(\theta)=1-cos^{2}(\theta)

we can subtract a 1 from both sides of the equation so we end up with:

-cos(\theta)=-cos^{2}(\theta)

and we can now add cos^{2}(\theta)

to both sides of the equation so we get:

cos^{2}(\theta)-cos(\theta)=0

and we can solve this equation by factoring. We can factor cos(\theta) to get:

cos(\theta)(cos(\theta)-1)=0

and we can use the zero product property to solve this, so we get two equations:

Equation 1:

cos(\theta)=0

\theta=cos^{-1}(0)

\theta={\frac{\pi}{2}, \frac{3\pi}{2}}

Equation 2:

cos(\theta)-1=0

we add a 1 to both sides of the equation so we get:

cos(\theta)=1

\theta=cos^{-1}(1)

\theta=0

so we end up with three answers to this equation:

\theta={0, \frac{\pi}{2}, \frac{3\pi}{2}}

7 0
3 years ago
Answer the question below
butalik [34]

Answer:

x=-1

y=-5

Step-by-step explanation:

(7x+y)-(x+y)=-6

6x=-6

x=-1

-1+y=-6

y=-5

6 0
2 years ago
Read 2 more answers
Frank started out in his car travelling 45 mph. When Frank was 1/3 miles away, Daniel started out from the same point at 50 mph
Anna007 [38]

Time taken by Daniel to catch up with Frank is 4 minutes.

Step-by-step explanation:

The question is on relative speed; speed of a moving object with respect to another.

The two cars are travelling in the same direction at different speeds thus;

Relative speed = speed of Daniel - speed of Frank = 50-45= 5 mph

The time which the two meet = distance/ relative speed

Distance = 1/3 miles, which equals 0.33 miles

Time taken by Daniel to catch up with Frank is = 0.33/5 =0.066 hours = 4 minutes.

Learn More

Relative speed: brainly.com/question/10681729

Keywords: car, travelling, miles,started at the same point,catch up with

#LearnwithBrainly

6 0
4 years ago
Read 2 more answers
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