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3 years ago

I need help with this problem. How do I do it?

Mathematics

1 answer:

Anna11 [10]3 years ago

8 0

Answer:

Step-by-step explanation:

For the area of a rectangle we use A = L* W

We know area or A = 420

and we know length or L = 21

Now we need to find the width or W

(420) = (21) * W

Divide both sides of the equation by 21 to isolate the variable.

That leaves us with:

W = 20

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95% Confidence interval for the variance:

$3.6511\leq \sigma^2\leq 34.5972$

95% Confidence interval for the standard deviation:

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Step-by-step explanation:

We have to calculate a 95% confidence interval for the standard deviation σ and the variance σ².

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$\chi_{0.025}=1.6899\\\\\chi_{0.975}=16.0128$

Then, the confidence interval can be calculated as:

$\dfrac{ (8 - 1) 8.3521}{ 16.0128} \leq \sigma^2 \leq \dfrac{ (8 - 1) 8.3521}{1.6899}\\\\\\3.6511\leq \sigma^2\leq 34.5972$

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