Y = number of yellow marbles
r = number of red marbles
The total number of marbles
y+r=61
The number of yellow marbles compared to red.
y=2r+4
Substitute the second equation into the first equation because they are the same variable and, therefore, are the same number.
2r+4+r=61
Simplify
3r+4=61
Subtract 4 from both sides
3r=57
Divide both sides by three
r=19
We have the number of red marbles, but we are looking for the number of yellow marbles, so plug the 19 red marbles into either equation.
y=2(19)+4
or
y+19=61
Simplify
y=42
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Answer:
42 yellow marbles
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Equations:
y+r=61
y=2r+4
Answer:
b
Step-by-step explanation:
hope this helps
Answer:
Step-by-step explanation:
Hi there,
To get started, recall the area of a bound circle formula:
where r is radius of the circle. However, Juan used an approximate value of π, 3.14. So for our purposes, the formula becomes:
Juan measured the circle's <em>diameter</em>, so we can find radius from diameter first. Radius is simply twice the length of the diameter; from one circle endpoint to the center, to the endpoint across, making a straight line:
⇒ 
Now plug in to obtain area:
The area is 19.265 centimetres squared.
Cross-sections are the area shapes when you cut through a 3D volume; if you cut through a pipe perpendicular to where it flows, you can see it is a circle! If you cut straight through a cube, it would be a square, etc.
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thanks,
Therefore , the value of x = -1
A biased example: Asking students who are in line to buy lunch
An unbiased example: Asking students who are leaving/going to lunch(<em>NOT buying </em><em>lunch</em><em />).
But in this case, the answer choices can be... confusing.
Don't panic! You're given numbers and, of course, your use of logic.
Answer choice A: 100 students grades 6-8
Answer choice B: 20-30 students any <em>one</em> grade<em></em><em>
</em>Answer choice C: 5 students
<em></em>Answer choice D: 50 students grade 8
An unbiased example would be to choose students from <em>any grade.</em> So we can eliminate choices B and D.
Now, the question wants to <em>estimate how many people at your middle school buy lunch.</em> This includes the whole entire school, and if you are going to be asking people, you aren't just going to assume that if 5 people out of 5 people you asked bought lunch, the whole school buys lunch.
So, to eliminate all bias and/or error by prediction, answer choice A, the most number of students, is your answer.
