There is a relationship between confidence interval and standard deviation:

Where

is the mean,

is standard deviation, and n is number of data points.
Every confidence interval has associated z value. This can be found online.
We need to find the standard deviation first:

When we do all the calculations we find that:

Now we can find confidence intervals:

We can see that as confidence interval increases so does the error margin. Z values accociated with each confidence intreval also get bigger as confidence interval increases.
Here is the link to the spreadsheet with standard deviation calculation:
https://docs.google.com/spreadsheets/d/1pnsJIrM_lmQKAGRJvduiHzjg9mYvLgpsCqCoGYvR5Us/edit?usp=sharing
The smallest number of tiles Quintin will need in order to tile his floor is 20
The given parameters;
- number of different shapes of tiles available = 3
- area of each square shape tiles, A = 2000 cm²
- length of the floor, L = 10 m = 1000 cm
- width of the floor, W = 6 m = 600 cm
To find:
- the smallest number of tiles Quintin will need in order to tile his floor
Among the three different shapes available, total area of one is calculated as;

Area of the floor is calculated as;

The maximum number tiles needed (this will be possible if only one shape type is used)

When all the three different shape types are used we can get the smallest number of tiles needed.
The minimum or smallest number of tiles needed (this will be possible if all the 3 different shapes are used)

Thus, the smallest number of tiles Quintin will need in order to tile his floor is 20
Learn more here: brainly.com/question/13877427
Answer:
cos(F) = 9/41
Step-by-step explanation:
The triangles are similar, so you know that ...
... cos(D) = cos(A) = 40/41.
From trig relations, you know ...
... cos(F) = sin(D)
and
... sin(D)² +cos(D)² = 1
So ...
... cos(F) = sin(D) = √(1 -cos(D)²) = √(1 -(40/41)²) = √(81/1681)
... cos(F) = 9/41
_____
The ratio for cos(A) tells you that you can consider AB=40, AC=41. Then, using the Pythagorean theorem, you can find BC = √(41² -40²) = √81 = 9.
From the definition of the cosine, you know cos(C) = BC/AC = 9/41. Because the triangles are similar, you know
... cos(F) = cos(C) = 9/41
The second question:
Consider the division expression
. Select all multiplication equations that correspond to this division expression.


Answer:
1. See Explanation
2.
and 
Step-by-step explanation:
Solving (a):
Given


Required
Interpret
in 2 ways
<u>Interpretation 1:</u> Number of groups if there are 5 students in each
<u>Interpretation 2:</u> Number of students in each group if there are 5 groups
<u>Solving the quotient</u>


<u>For Interpretation 1:</u>
The quotient means: 12 groups
<u>For Interpretation 2:</u>
The quotient means: 12 students
Solving (b):
Given

Required
Select all equivalent multiplication equations
Let ? be the quotient of t 
So, we have:

Multiply through by 2


Rewrite as:
--- This is 1 equivalent expression
Apply commutative law of addition:
--- This is another equivalent expression