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3 years ago

When 21 is subtracted from the square of a number, the result is 4 times the number. Find the positive solution.

Mathematics

1 answer:

wel3 years ago

7 0

Let x = your number.

x^2 - 21 = 4x. Subtract 4x from both sides.

x^2 - 4x - 21 = 0. Factor.

(x - 7) (x + 3) = 0. Set each term to 0.

x + 3 = 0. Subtract 3 from both sides.

x = -3. This is the negative solution.

Set the other term equal to zero.

x - 7 = 0. Add 7 to each side.

x = 7. This is the positive solution.

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Answer:

The 98% confidence interval estimate of the proportion of adults who use social media is (0.56, 0.6034).

Step-by-step explanation:

In a sample with a number n of people surveyed with a probability of a success of $\pi$ , and a confidence level of $1-\alpha$ , we have the following confidence interval of proportions.

$\pi \pm z\sqrt{\frac{\pi(1-\pi)}{n}}$

In which

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The lower limit of this interval is:

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The upper limit of this interval is:

$\pi + z\sqrt{\frac{\pi(1-\pi)}{n}} = 0.5817 + 2.327\sqrt{\frac{0.5817*4183}{2809}} = 0.6034$

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Here is you're answer:

In order to get you're answer you need to find the common denominator then add.

$\frac{1}{6} + \frac{3}{8}$
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Simplify:
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$= \frac{13}{24}$

Therefore you're answer is option D "13/24."

Hope this helps!

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