Answer:
a.1.90 years
Step-by-step explanation:
We have that to find our
level, that is the subtraction of 1 by the confidence interval divided by 2. So:

Now, we have to find z in the Ztable as such z has a pvalue of
.
So it is z with a pvalue of
, so 
Now, find the margin of error M as such

In which
is the standard deviation of the population and n is the size of the sample.
In this question:

So

So the correct answer is:
a.1.90 years
For this case we have that by definition, it is called arcsine (arcsin) from a number to the angle that has that number as its sine.
We must find the
. Then, we look for the angle whose sine is
.
We have to, by definition:

So, we have to:

Answer:
Option B
If we have 420 books for every 7 shelves and are looking for how many books are on 4 shelves, we need to set up fractional proportions.
We have 7 shelves for every 420 books, so we will have our first fraction like this:
7/420.
We also have 4 shelves for every x books, so our second fraction will be 4/x.
Set these fractions up as an equation.
7/420 = 4/x
To solve for x, we need to cross multiply the numerators of one fraction with the denominators of the other fraction.
In other words, multiply the top number of one fraction by the bottom number of the other question.
It should look like this:
7(x)
420(4)
7(x) = 7x
420(4) = 1680
Set your products up as an equation.
7x = 1680
Now to solve for x, we need to simplify.
Currently, x is being multiplied by 7.
To get x alone, divide 7x by 7.
Remember, what you do to one side of an equation, you must do to the other, so divide 1680 by 7.
7x / 7 = x
1680 / 7 = 240
You are left with:
x = 240.
For every 4 shelves you have 240 books.
I hope this helps!
Answer:
5
Step-by-step explanation:
It's the one that's missing.
Hope I helped!
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