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Valentin [98]
3 years ago
9

Which of the following is an example of a matched pairs design? A. A teacher calculates the average scores of students on a pair

of tests and wishes to see if this average is larger than 80%. B. A teacher compares the pre-test and post-test scores of students. C. A teacher compares the scores of students using a computer based method of instruction with scores of other students using a traditional method of instruction. D. A teacher compares the scores of students in her class on a standardized test with the national average score.
Mathematics
1 answer:
Mashutka [201]3 years ago
5 0

Answer:

B. A teacher compares the pre-test and post-test scores of students

Step-by-step explanation:

the answer is true, because it is a good example to compare the tests between students, we know that a matching pair design is a random model and is used when the experiment allows grouping subjects in pairs based on a variable and each pair will receive randomly a different handling, the answer A is not true because in the example all students are uniformly averaged and the variable is not correlated with subgroups, option c is incorrect because the variable was not randomized and generates classification bias and the option d is incorrect because the teacher compares a small sample as her class with a score of a total sample, but does not intervene on her students when selecting the corresponding group

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I have nooooo clue, please help
Aleksandr-060686 [28]

Answer:

case a) x^{2}=3y ----> open up

case b) x^{2}=-10y ----> open down

case c) y^{2}=-2x ----> open left

case d) y^{2}=6x ----> open right

Step-by-step explanation:

we know that

1) The general equation of a vertical parabola is equal to

y=a(x-h)^{2}+k

where

a is a coefficient

(h,k) is the vertex

If a>0 ----> the parabola open upward and the vertex is a minimum

If a<0 ----> the parabola open downward and the vertex is a maximum

2) The general equation of a horizontal parabola is equal to

x=a(y-k)^{2}+h

where

a is a coefficient

(h,k) is the vertex

If a>0 ----> the parabola open to the right

If a<0 ----> the parabola open to the left

Verify each case

case a) we have

x^{2}=3y

so

y=(1/3)x^{2}

a=(1/3)

so

a>0

therefore

The parabola open up

case b) we have

x^{2}=-10y

so

y=-(1/10)x^{2}

a=-(1/10)

a

therefore

The parabola open down

case c) we have

y^{2}=-2x

so

x=-(1/2)y^{2}

a=-(1/2)

a

therefore

The parabola open to the left

case d) we have

y^{2}=6x

so

x=(1/6)y^{2}

a=(1/6)

a>0

therefore

The parabola open to the right

3 0
2 years ago
Which angle has a sine of -1/2 and a cosine of -√3/2
Sergeeva-Olga [200]
\sin x=-\dfrac{1}{2} < 0\\\\\cos x=-\dfrac{\sqrt3}{2} < 0\\\\therefore\ x\in(180^o;\ 270^o)

\text{We know:}\ \tan x=\dfrac{\sin x}{\cos x}\\\\\text{therefore:}\ \tan x=\dfrac{-\frac{1}{2}}{-\frac{\sqrt3}{2}}=\dfrac{1}{2}\cdot\dfrac{2}{\sqrt3}=\dfrac{1}{\sqrt3}\cdot\dfrac{\sqrt3}{\sqrt3}=\dfrac{\sqrt3}{3}

\tan x=\dfrac{\sqrt3}{3}\Rightarrow x=30^o+180^o\cdot k;\ k\in\mathbb{Z}

x\in(180^o;\ 270^o)\ therefore\ \boxed{x=30^o+180^o=210^o}
8 0
3 years ago
One pitcher of smoothies uses 3 cups of berries. How many pitchers of smoothies can you make with 10 cups of berries?
Fed [463]
Answer is 10 cups divided by 3 cups = 1 pitcher smoothie,
10/3 or 3-1/3 pitchers of smoothies
I don’t see your choices so my answers might not be what you have to chose from
7 0
2 years ago
Two different numbers can be written in the form 2^n. The sum of the numbers is 40. What is the difference of the numbers?
Greeley [361]

Answer:

24

Step-by-step explanation:

If you use 2^5 = 32 and 2^3 = 8.

32 + 8 = 40

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Answer:

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Step-by-step explanation:

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3 years ago
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