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-Dominant- [34]
2 years ago
9

A national survey of middle school students asks how many hours of sleep they get on school nights. Which sample ​best​ represen

ts the population?
a.) A group of 941 students in eighth grade in a certain town
b.) A group of 886 students in sixth grade in a certain county
c.) A group of 795 students in seventh grade in different states
d.) A group of 739 students in different middle school grade levels from various states
Mathematics
1 answer:
mariarad [96]2 years ago
5 0

Answer:

D

Step-by-step explanation:

It wouldnt be a single grade being surveyed so we would choose d in additon a and b isnt national since it says 'in a certain town' and 'in a certain county'.

Which leaves you with D.

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I don’t understand how to proof Cpctc or answer the questions
n200080 [17]
I think that first you need to understand what CPCTC is used for.

Let's start with the definition of congruent triangles.

Definition of congruent triangles
Two triangles are congruent if each side of one triangle is congruent to a corresponding side of the other triangle and each angle of one triangle is congruent to a corresponding angle of the other triangle.

A definition works two ways.
1) If you are told the sides and angles of one triangle are congruent to the corresponding sides and angle of a second triangle, then you can conclude the triangles are congruent.
2) If you are told the triangles are congruent, then you can conclude 6 statements of congruence, 3 for sides and 3 for angles.

Now let's see what CPCTC is and how it works.
CPCTC stands for "corresponding parts of congruent triangles are congruent."
The way it works is this. You can prove triangles congruent by knowing fewer that 6 statements of congruence. You can use ASA, SAS, AAS, SSS, etc. Once you prove two triangles congruent, then by the definition of congruent triangles, there are 6 congruent statements. That is where CPCTC comes in. Once you prove the triangles congruent, then you can conclude two corresponding sides or two corresponding angles are congruent by CPCTC. These two corresponding parts were not involved in proving the triangles congruent.

Problem 1.

Statements                                        Reasons
1. Seg. AD perp. seg. BC               1. Given
2. <ADB & <ADC are right angles     2. Def. of perp. lines
3. <ADB is congr. <ADC                 3. All right angles are congruent
4. Seg. BD is congr. seg CD           4. Given
5. Seg. AD is congr. seg. AD        5. Congruence of segments is reflexive
6. Tr. ABD is congr. tr. ACD           6. SAS
7. Seg. AB is congr. seg. AC        7. CPCTC

4 0
3 years ago
Find the measures of the supplementary angles that satisfy each case.
seropon [69]

Answer:

67.5°, 107.5°

Step-by-step explanation:

For supplementary angles, their sum equals 180°.

Let x be the first angle and y be the second angle, then

x + y = 180°.

It is given that x = y + 45°.

So x + y = 180°

substituting x into the equation, we have

y + 45° + y = 180°

simplifying, we have

2y + 45° = 180°

collecting like terms, we have

2y = 180° - 45°

2y = 135°

dividing through by 2, we have

y = 135°/2

y = 67.5°

Since y = 67.5°

then x = y + 45°

x = 67.5° + 45°

x = 107.5°

3 0
3 years ago
A=1/2bh for b<img src="https://tex.z-dn.net/?f=a%3D1%2F2bh%20for%20b" id="TexFormula1" title="a=1/2bh for b" alt="a=1/2bh for b"
valkas [14]
Times both sides by 2
2A=bh
divide both sides b h
\frac{2A}{h}=b
b=\frac{2A}{h}
5 0
3 years ago
Quation that show an estimate of 7,203+299
Dmitry [639]

The two numbers are very near 7200 and 300. The sum of those is a good estimate of your sum:

... 7200 + 300 = 7500

_____

If you're taught methods of addition that include "make a ten" or "make a hundred", you know you can "borrow" a 1 from 7203 (making it 7202) and loan that 1 to 299 to make it 300. Now, you know your sum is exactly 7202+300 = 7502, with no estimation necessary.

8 0
2 years ago
Read 2 more answers
If I have 500 animals and gave away 267 how much would I have left
skad [1K]
You will have 233 animals left.
5 0
2 years ago
Read 2 more answers
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