To find the area of a regular polygon, all you have to do is follow this simple formula: area = 1/2 x perimeter x apothem. Here is what it means: Perimeter = the sum of the lengths of all the sides.

4 0

3 years ago

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AB = 2x-5 BC = 6x AC = 27

OlgaM077 [116]

Answer:

correct answer is x = 2.75

Step-by-step explanation:

Given;

AB = 2x-5

BC = 6x

AC = 27

Hence,

=> AC = AB + BC

=> 27 = 2x-5 + 6x

=> 27 = 8x-5

=> 27-5 = 8x

=> 22 = 8x

=> 22/8 = x

=> 11/4 = x

2.75 = x

3 0

3 years ago

An unconfined compression test was performed to determine the average strength of concrete cylinders (in psi). It is believed th

Ronch [10]

Answer:

Explained below.

Step-by-step explanation:

(1)

The confidence level is, 91%.

Compute the value of α as follows:

$\text{Confidence level}\% =(100-\alpha \%)\\\\91% = 100-\alpha \%\\\\\alpha \%=100-91\%\\\\\alpha \%=9\%\\\\\alpha =0.09$

(2)

As the population standard deviation is provided, i.e. σ = 256 psi, the z value would be appropriate.

The z value for α = 0.09 is,

z = 1.69

(3)

Compute the 91% confidence interval as follows:

$CI=\bar x\pm z_{\alpha/2}\cdot\frac{\sigma}{\sqrt{n}}$

$=3000\pm 1.69\cdot\frac{256}{\sqrt{70}}\\\\=3000\pm 51.71\\\\=(2942.29, 3057.71)$

(4)

The 91% confidence interval for population mean implies that there is a 0.91 probability that the true value of the mean is included in the interval, (2942.29, 3057.71) psi.

8 0

3 years ago