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Probability-and-statistics/639646: ....
A study is conducted to determine if adults over 50 years old with higher total cholesterol levels are more hostile than those with lower cholesterol levels. A group of 100 adults is randomly selected and their level of hostility as well as their cholesterol levels is recorded.
I. What is the population?
II. What is the sample?
III. Is the study observational or experimental? Justify your answer.
IV. What are the variables?
V. For each of those variables, what level of measurement (nominal, ordinal, interval, or ratio) was used to obtain data from these variables? 1 solutions
Answer 402857 by jim_thompson5910(28476) on 2012-08-21 20:16:29 (Show Source):
You can put this solution on YOUR website!I. What is the population?
The set of all 50 year old adults.
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II. What is the sample?
The 100 people randomly selected (from the population) for this study
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III. Is the study observational or experimental? Justify your answer.
It's an observation because the researchers are simply looking at data and they are NOT manipulating the subjects in any way. They are also NOT splitting the subjects into two groups (the control and experimental group.
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IV. What are the variables?
The variables are cholesterol level and hostility level.
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V. For each of those variables, what level of measurement (nominal, ordinal, interval, or ratio) was used to obtain data from these variables?
Cholesterol Level: Ratio (since they can be ordered, the differences make sense, and there's a 0)
Hostility Level: Ordinal (assuming you have something like "not hostile", "somewhat hostile" and "very hostile")
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Equations/639641: Find an equation of the line containing the given pair of points.
(2,1) and (6,4) 1 solutions
Answer 402841 by jim_thompson5910(28476) on 2012-08-21 18:08:44 (Show Source):
You can put this solution on YOUR website!
First let's find the slope of the line through the points ) and
Note: ) is the first point ) . So this means that  and  .
Also, ) is the second point ) . So this means that  and  .
 Start with the slope formula.
 Plug in  ,  ,  , and
 Subtract  from  to get
 Subtract  from  to get
So the slope of the line that goes through the points ) and ) is
Now let's use the point slope formula:
 Start with the point slope formula
 Plug in  ,  , and
 Distribute
 Multiply
 Add 1 to both sides.
 Combine like terms. note: If you need help with fractions, check out this solver.
So the equation that goes through the points ) and ) is
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Functions/639388: Given that a(x)=x^2-5 and b(x)=6x+1
Evaluate (aob)(x) and (boa)(x)
I understand that this is (fog)(x) and (gof)(x)
So a(b(x)) is how I should insert the functions, but I'm not sure if I'm doing it right? Please help,
Thank You 1 solutions
Answer 402716 by jim_thompson5910(28476) on 2012-08-21 00:29:04 (Show Source):
You can put this solution on YOUR website!The idea is to start with the outer function first. Then replace the input with the inner function.
a(x) = x^2-5
a(b(x)) = (b(x))^2-5 ... Replace ALL 'x' terms with b(x)
a(b(x)) = (6x+1)^2-5 ... Replace b(x) on the right side with 6x+1 (since b(x) = 6x+1)
I'll let you expand and simplify this.
-------------------------------------------------------
Now we reverse what we just did
b(x)=6x+1
b(a(x))=6(a(x))+1
b(a(x))=6(x^2-5)+1
I'll let you simplify.
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Sequences-and-series/639363: Solve for the next two numbers in the following number sequence: 1728, 1000, 512, 216, _, _. 1 solutions
Answer 402710 by jim_thompson5910(28476) on 2012-08-20 23:39:57 (Show Source):
You can put this solution on YOUR website!Each number is a perfect cube. Notice how 12^3 = 1728, 1000 = 10^3, 512 = 8^3, 216 = 6^3
So the form is n^3 where 'n' is some integer. But we're only focusing on positive even integers and we're counting down to the next even integer each time. Moreover, we're starting at 12. So 'n' becomes -2n+12 where n starts at n = 0. If you want to start at n = 1, then you have to add 2 to 12 to get -2n+14
So the sequence follows the form (-2n+14)^3 where n is a positive integer and n starts at n = 1
We can see that when n = 1, (-2n+14)^3 = (-2*1+14)^3 = 1728
When n = 2, (-2n+14)^3 = (-2*2+14)^3 = 1000
etc etc
all the way up to n = 4, (-2n+14)^3 = (-2*4+14)^3 = 216
The next two terms are
n = 5, (-2n+14)^3 = (-2*5+14)^3 = 64
and
n = 6, (-2n+14)^3 = (-2*6+14)^3 = 8
=======================================================
Answer:
So the updated sequence is
1728, 1000, 512, 216, _ 64_, _ 8_
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Functions/639319: State f(x) and g(x) for which f(x)*g(x)=2x^2+11x-6. How do you go about doing this problem? Thank you! 1 solutions
Answer 402690 by jim_thompson5910(28476) on 2012-08-20 21:06:24 (Show Source):
You can put this solution on YOUR website!Hint:
Factor 2x^2+11x-6
You do this by multiplying 2 and -6 to get -12. Then you find two numbers that multiply to -12 and add to 11. These two numbers are 12 and -1
So
2x^2+11x-6
2x^2+12x-x-6
Now factor by grouping
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real-numbers/639247: I have a fraction which is 9/16 and both of the numbers have the square root sign. can you tell me whether its natural whole interger rational or irrational? 1 solutions
Answer 402684 by jim_thompson5910(28476) on 2012-08-20 20:51:46 (Show Source):
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real-numbers/639225: is the square root of 11 a natural whole interger rational or irrational number? 1 solutions
Answer 402647 by jim_thompson5910(28476) on 2012-08-20 18:33:28 (Show Source):
You can put this solution on YOUR website!You CANNOT write 11 in the form of  where 'x' is some integer. So it is an irrational number
You can see this because  approximately, and the decimal digits go on forever without repeating a specific pattern.
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Sequences-and-series/639183: Find a set of at least 5 data values that has a mean of 20 and a standard deviation of 6. 1 solutions
Answer 402616 by jim_thompson5910(28476) on 2012-08-20 17:05:18 (Show Source):
You can put this solution on YOUR website!Start with the set
20,20,20,20,20
That has a mean of 20, but a standard deviation of 0. Then increase one value to get 21, but decrease another value (to balance things out) to get 19.
So we might have
19, 20, 20, 20, 21
Now find the standard deviation. It will be roughly 0.70710678 (use a calculator here).
Repeat the last 3 steps to find another standard deviation.
We can keep going and do this by trial and error, but there's a much easier way
This way involves using the definition of sample standard deviation.
sigma = sqrt(sum((x-mu)^2)/(n-1))
6 = sqrt(sum((x-mu)^2)/(n-1))
6^2 = sum((x-mu)^2)/(n-1)
36 = sum((x-mu)^2)/(n-1)
36 = sum((x-mu)^2)/(5-1)
36 = sum((x-mu)^2)/4
36*4 = sum((x-mu)^2)
144 = sum((x-mu)^2)
sum((x-mu)^2) = 144
(x1-mu)^2+(x2-mu)^2+(x3-mu)^2+(x4-mu)^2+(x5-mu)^2 = 144
(x1-20)^2+(x2-20)^2+(x3-20)^2+(x4-20)^2+(x5-20)^2 = 144
(20-x-20)^2+(20-20)^2+(20-20)^2+(20-20)^2+(20+x-20)^2 = 144
(20-x-20)^2+(0)^2+(0)^2+(0)^2+(20+x-20)^2 = 144
(-x)^2+0+0+0+(x)^2 = 144
x^2 + x^2 = 144
2x^2 = 144
x^2 = 144/2
x^2 = 72
x = sqrt(72)
x = 8.48528137423857
So the data set of
20,20,20,20,20
becomes
20-8.48528137423857,20,20,20,20+8.48528137423857
11.5147186257614,20,20,20,28.48528137423857
So the data set
11.5147186257614,20,20,20,28.48528137423857
has a mean of 20 and a standard deviation of (roughly) 6
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If you want to be exact, then the data set
20-sqrt(72), 20, 20, 20, 20+sqrt(72)
has a mean of 20 and a standard deviation of exactly 6
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