<span><span>DO use multiplication sign '*' (the STAR) symbol. For the simplifier, xy is NOT the same as x*y or yx. Simplifier thinks that xy is a separate variable. Good example: x*y-y*(x+2). Bad example: xy-y(x+2).</span>DO use '*' when multiplying a variable by an expression in parentheses: x*(x+2). Otherwise, my simplifier will think that you are trying to use a function and will become confused.Use parentheses liberally to avoid any ambiguity. (x+y)/(x-y) is NOT the same as x+y/x-y. x+y/x-y means x+(y/x)-y.</span>Operations<span>Use '*' (STAR) for multiplication. 2*3 is legal, 2x3 will be misunderstood.Use '^' (CARET) for power. 2^3 means 2 to degree of 3, or 8.Use '/' (FORWARD SLASH) for divisionOnly '(' and ')' (parentheses) are allowed for grouping terms. Curly or square brackets are used for other purposes.</span>
Operation priority: + and - have lowest priority, * and / h
Good Examplesx*y-x*(y+2) <-- '*' is used for multiplications
a^b*3 <-- means (a to the degree of b) multiplied by 3
Bad examples<span>xy-yx <-- variable xy and variable yx are different variables
y(x-2) <-- simplifier will think that it is function y of x-2.</span>
Answer:
Top 3%: 4.934 cm
Bottom 3%: 4.746 cm
Step-by-step explanation:
Problems of normally distributed samples are solved using the z-score formula.
In a set with mean
and standard deviation
, the zscore of a measure X is given by:
![Z = \frac{X - \mu}{\sigma}](https://tex.z-dn.net/?f=Z%20%3D%20%5Cfrac%7BX%20-%20%5Cmu%7D%7B%5Csigma%7D)
The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.
In this problem, we have that:
![\mu = 4.84, \sigma = 0.05](https://tex.z-dn.net/?f=%5Cmu%20%3D%204.84%2C%20%5Csigma%20%3D%200.05)
Top 3%
Value of Z when Z has a pvalue of 1 - 0.03 = 0.97. So X when Z = 1.88.
![Z = \frac{X - \mu}{\sigma}](https://tex.z-dn.net/?f=Z%20%3D%20%5Cfrac%7BX%20-%20%5Cmu%7D%7B%5Csigma%7D)
![1.88 = \frac{X - 4.84}{0.05}](https://tex.z-dn.net/?f=1.88%20%3D%20%5Cfrac%7BX%20-%204.84%7D%7B0.05%7D)
![X - 4.84 = 0.05*1.88](https://tex.z-dn.net/?f=X%20-%204.84%20%3D%200.05%2A1.88)
![X = 4.934](https://tex.z-dn.net/?f=X%20%3D%204.934)
Bottom 3%
Value of Z when Z has a pvalue of 0.03. So X when Z = -1.88.
![Z = \frac{X - \mu}{\sigma}](https://tex.z-dn.net/?f=Z%20%3D%20%5Cfrac%7BX%20-%20%5Cmu%7D%7B%5Csigma%7D)
![-1.88 = \frac{X - 4.84}{0.05}](https://tex.z-dn.net/?f=-1.88%20%3D%20%5Cfrac%7BX%20-%204.84%7D%7B0.05%7D)
![X - 4.84 = 0.05*(-1.88)](https://tex.z-dn.net/?f=X%20-%204.84%20%3D%200.05%2A%28-1.88%29)
![X = 4.746](https://tex.z-dn.net/?f=X%20%3D%204.746)
Lets get started :)
The First question:
Diameter = 20 ft
Radius =
![\frac{1}{2}](https://tex.z-dn.net/?f=%20%5Cfrac%7B1%7D%7B2%7D%20)
of 20 (diameter) = 20 ft
Area formula of a circle is
A =
![\pi](https://tex.z-dn.net/?f=%20%5Cpi%20)
r²
=
![\pi](https://tex.z-dn.net/?f=%20%5Cpi%20)
(10)²
=100
![\pi](https://tex.z-dn.net/?f=%20%5Cpi%20)
ft²
≈ 314 ft²The answer will be the second optionThe Second question:
radius of circle = 12mm divided into 20 sectors area
A =
![\pi](https://tex.z-dn.net/?f=%20%5Cpi%20)
r²
=
![\pi](https://tex.z-dn.net/?f=%20%5Cpi%20)
(12)²
= 144
![\pi](https://tex.z-dn.net/?f=%20%5Cpi%20)
ft²
Divide into 20 equal sector areas =
≈ 22.6 mm²Your answer will be the third optionThe Third Question:
90°, sector area = 36
![\pi](https://tex.z-dn.net/?f=%20%5Cpi%20)
, Radius = ?
![\frac{angle}{360} = \frac{sector}{ \pi (r)^2}](https://tex.z-dn.net/?f=%20%5Cfrac%7Bangle%7D%7B360%7D%20%3D%20%5Cfrac%7Bsector%7D%7B%20%5Cpi%20%28r%29%5E2%7D%20)
![\frac{90}{360} = \frac{36 \pi }{ \pi r^2}](https://tex.z-dn.net/?f=%20%5Cfrac%7B90%7D%7B360%7D%20%3D%20%5Cfrac%7B36%20%5Cpi%20%7D%7B%20%5Cpi%20r%5E2%7D%20)
![\pi](https://tex.z-dn.net/?f=%20%5Cpi%20)
and
![\pi](https://tex.z-dn.net/?f=%20%5Cpi%20)
cancels out
We can now cross multiply
360 × 36 = 90r²
12960 = 90r²
Divide by 90 on either side
![\frac{12960}{90} = \frac{90r^2}{90}](https://tex.z-dn.net/?f=%20%5Cfrac%7B12960%7D%7B90%7D%20%3D%20%5Cfrac%7B90r%5E2%7D%7B90%7D%20)
144 = r²
Take squareroot
x = 12 inYour answer will be the third option