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leva [86]
3 years ago
14

Help!! Can someone explain this to me I’m not getting it.

Mathematics
2 answers:
chubhunter [2.5K]3 years ago
3 0

Answer:

A. 99 sq cm

Step-by-step explanation:

Area of geometric shape

= 2 times the area of one triangle with base a and height c

+ 2 times the area of one triangle with base c and height b

+ Area of rectangle with dimensions a and c.

= 2 \times  \frac{1}{2} ac + 2 \times  \frac{1}{2} bc + ac \\  \\  = ac + bc + ac \\  \\  = 2ac + bc \\  \\  = 2(13)(3) + 7(3) \\  \\  = 78 + 21 \\  \\  = 99 \: sq \: cm

Marysya12 [62]3 years ago
3 0
<h3>Answer: Choice A) 99 square cm.</h3>

=============================================================

Explanation:

The rectangular base has area of length*width = a*c = 13*3 = 39 square cm. Let m = 39 since we'll use it later.

The triangles on the left and right sides have an area of base*height/2 = c*b/2 = 3*7/2 = 21/2 = 10.5 sq cm. They combine to an area of 2*10.5 = 21 sq cm. Let n = 21 since we'll use it later.

The triangles in the north and south positions have base 'a' and height 'c', so the area of each is base*height/2 = a*c/2 = 13*3/2 = 39/2 = 19.5 sq cm. That means the two north and south triangles add up to 19.5+19.5 = 39 sq cm. Let p = 39 since we'll use it later.

Overall, we have a total area of m+n+p = 39+21+39 = 99

The area of this flat 2D figure is 99 sq cm. If we folded along the dashed lines, then we'd get a 3D rectangular pyramid that has surface area of 99 sq cm. The surface area is the amount of material along the outside of the 3D figure. Or you can think of it like saying "If we painted all four sides of the 3D pyramid, then we cover 99 cm^2 of area".

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Steps to solve:

x^3 - 125 = 0

~Add 125 to both sides

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x = 5

Best of Luck!

8 0
3 years ago
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Answer:

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So on this case the 95% confidence interval would be given by (15.641;18.359)    

And since the lower limit for the confidence interval is higher than 15 we can conclude that at 5% of significance the true mean is higher than 15 cm

Step-by-step explanation:

Previous concepts

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".

The margin of error is the range of values below and above the sample statistic in a confidence interval.

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

\bar X=17 represent the sample mean

\mu population mean (variable of interest)

s=1.9 represent the sample standard deviation

n=10 represent the sample size  

Confidence interval

The confidence interval for the mean is given by the following formula:

\bar X \pm t_{\alpha/2}\frac{s}{\sqrt{n}}   (1)

In order to calculate the critical value t_{\alpha/2} we need to find first the degrees of freedom, given by:

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Since the Confidence is 0.95 or 95%, the value of \alpha=0.05 and \alpha/2 =0.025, and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-T.INV(0.025,9)".And we see that t_{\alpha/2}=2.262

Now we have everything in order to replace into formula (1):

17-2.262\frac{1.9}{\sqrt{10}}=15.641    

17+2.262\frac{1.9}{\sqrt{10}}=18.359    

So on this case the 95% confidence interval would be given by (15.641;18.359)    

And since the lower limit for the confidence interval is higher than 15 we can conclude that at 5% of significance the true mean is higher than 15 cm

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Answer:

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Step-by-step explanation:

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