2 years ago

Can someone pls help for brainlest

Mathematics

1 answer:

gregori [183]2 years ago

5 0

Diameter of the semicircle = 10 km.

Explanation: perimeter of semicircle = 1 2

the circumference + diameter Given: perimeter of semicircle = 25.7 k m

Circumference of circle with radius r = 2 π r where 2 r = diameter ⇒ 25.7 = 22 π r + 2 r ⇒ 25.7 = π r + 2 r = r ( π + 2 ) ⇒ 25.7 = r ( 3.14 + 2 ) = r ( 5.14 ) ⇒ r = =5m ⇒d i a m e t e r = 2 r = 10 k m

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The 90% confidence interval estimate of the mean annual income of all company presidents is ($579,545, $590,580).

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The information provided is:

$n=80\\\sigma=30,000\\\bar x=585062.50\\\text{Confidence level} = 90\%$

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Compute the 90% confidence interval estimate of the mean annual income of all company presidents as follows:

$CI=\bar x\pm z_{\alpha/2}\cdot\frac{\sigma}{\sqrt{n}}\\\\=585062.50\pm 1.645\times\frac{30000}{\sqrt{80}}\\\\=585062.50\pm5517.50\\\\=(579545, 590580)$