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4 years ago

Help! You don't have to answer everything, just answer maybe 23 and explain to me how you got it.

Mathematics

1 answer:

Vinvika [58]4 years ago

8 0

23 is 40 degrees
because it’s vertical to angle AOF and when two angels r vertical, they r equal

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The city of Madison regularly checks the quality of water at swimming beaches located on area lakes. Fifteen times the concentra

Maksim231197 [3]

Answer:

The sample standard deviation is 393.99

Step-by-step explanation:

The standard deviation of a sample can be calculated using the following formula:

$s=\sqrt[ ]{\frac{1}{N-1} \sum_{i=1}^{N}(x_{i}-{\displaystyle \textstyle {\bar {x}}}) ^{2} }$

Where:

$s=$ Sample standart deviation

$N=$ Number of observations in the sample

${\displaystyle \textstyle {\bar {x}}}=$ Mean value of the sample

and $\sum_{i=1}^{N}(x_{i}-{\displaystyle \textstyle {\bar {x}}}) ^{2} }$ simbolizes the addition of the square of the difference between each observation and the mean value of the sample.

Let's start calculating the mean value:

$\bar {x}=\frac{1}{N} \sum_{i=1}^{N}x_{i}$

$\bar {x}=\frac{1}{15}*(180+1600+90+140+50+260+400+90+380+110+10+60+20+340+80)$

$\bar {x}=\frac{1}{15}*(3810)$

$\bar {x}=254$

Now, let's calculate the summation:

$\sum_{i=1}^{N}(x_{i}-\bar {x}) ^{2} }=(180-254)^2+(1600-254)^2+(90-254)^2+...+(80-254)^2$

$\sum_{i=1}^{N}(x_{i}-\bar {x}) ^{2} }=2173160$

So, now we can calculate the standart deviation:

$s=\sqrt[ ]{\frac{1}{N-1} \sum_{i=1}^{N}(x_{i}-{\displaystyle \textstyle {\bar {x}}}) ^{2} }$

$s=\sqrt[ ]{\frac{1}{15-1}*(2173160)}$

$s=\sqrt[ ]{\frac{2173160}{14}}$

$s=393.99$

The sample standard deviation is 393.99

3 0

4 years ago

. Question 1.1. What is the first step in solving x2 + 2x + 3 = 0 by completing the square?. (Points : 1). Factor the left side.

Assoli18 [71]

U r going to subtract 3 from each side of the equation....leaving you with :
x^2 + 2x = -3

6 0

4 years ago

Read 2 more answers

Factor by grouping:

BARSIC [14]

$(x-y)^2=x^2-2xy+y^2\\---------------------------\\\\4-12r+9r^2=2^2-2\cdot2\cdot3r+(3r)^2=(2-3r)^2$

$other\ method:\\\\4-12r+9r^2=4-6r-6r+9r^2=2(2-3r)-3r(2-3r)\\\\=(2-3r)(2-3r)=(2-3r)^2$

3 0

3 years ago

Read 2 more answers

3(x+4)-1=-7 plz help

tatiyna

Answer:

x = -6

Step-by-step explanation:

3(x+4)-1=-7

Add 1 to each side

3(x+4)-1+1=-7+1

3(x+4)=-6