25 points!! Will give Brainliest!! Help please!!!

Mathematics

1 answer:

fredd [130]3 years ago

6 0

What I did for this question is I set up ans equation. 5x-7 + 3x+11 = 180 and I added the Xs and and I added 11 to -7. Then I got 8x+4=180. I then "-4" on both sides and then divided 8 by 176. Getting X as 22. We now know X and we put 22 into the equation for D which is "3x+11" getting 77 degrees. Hope this helped!

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A physicist examines 25 water samples for nitrate concentration. The mean nitrate concentration for the sample data is 0.165 cc/

xz_007 [3.2K]

Answer:

The 80% confidence interval for the the population mean nitrate concentration is (0.144, 0.186).

Critical value t=1.318

Step-by-step explanation:

We have to calculate a 80% confidence interval for the mean.

The population standard deviation is not known, so we have to estimate it from the sample standard deviation and use a t-students distribution to calculate the critical value.

The sample mean is M=0.165.

The sample size is N=25.

When σ is not known, s divided by the square root of N is used as an estimate of σM:

$s_M=\dfrac{s}{\sqrt{N}}=\dfrac{0.078}{\sqrt{25}}=\dfrac{0.078}{5}=0.016$

The degrees of freedom for this sample size are:

$df=n-1=25-1=24$

The t-value for a 80% confidence interval and 24 degrees of freedom is t=1.318.

The margin of error (MOE) can be calculated as:

$MOE=t\cdot s_M=1.318 \cdot 0.016=0.021$

Then, the lower and upper bounds of the confidence interval are:

$LL=M-t \cdot s_M = 0.165-0.021=0.144\\\\UL=M+t \cdot s_M = 0.165+0.021=0.186$

The 80% confidence interval for the population mean nitrate concentration is (0.144, 0.186).

6 0

3 years ago

If angle x=55% and angle y=35, calculate the following 1.cos(x+y)

Setler79 [48]

Answer:

cos(X+Y) = cos(55+35) = cos(90) = 0

Step-by-step explanation:

cos(X+Y) = cosXcosY - sinXsinY

cos(55+35) = cos(55)cos(35) - sin(55)sin(35)

cos(55+35) = cos(55)cos(35) - cos(90-55)cos(90-35)

cos(55+35) = cos(55)cos(35) - cos(35)cos(55)

cos(55+35) = 0

cos(90) = 0

4 0

3 years ago

Write the standard form of the equation of the circle with the given characteristics. Center: (3, 5); Solution point: (−2, 17)

Angelina_Jolie [31]

$\text{we know that the general equation of the circle is }\\
\\
(x-h)^2+(y-k)^2=r^2\\
\\
\text{where, (h,k) is the center of the circle and r is the radius.}\\
\\
\text{Given that the centered of the circle is at }(h,k)=(3,5)\\
\text{and a solution point on circle is (-2,17).}\\
\\
\text{so the radius of the circle will be the distance between center and the }$

$\text{solution point. so using the distance formula, we have}\\
\\
\text{Radius, }r=\sqrt{(-2-3)^2+(17-5)^2}\\
\\
\Rightarrow r=\sqrt{25+144}\\
\\
\Rightarrow r=\sqrt{169}\\
\\
\Rightarrow r=13\\
\\
\text{Hence using the standard for of circle, equation of circle with center}\\
(h,k)=(3,5) \text{ and radius r=13 is}\\
\\
(x-3)^2+(y-5)^2=(13)^2\\
\\
\Rightarrow (x-3)^2+(y-5)^2=169$