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ira [324]
3 years ago
6

What two numbers' sum=-4 and product=-2

Mathematics
1 answer:
n200080 [17]3 years ago
7 0

Let <em>a</em> and <em>b</em> be the two numbers. Then

<em>a</em> + <em>b</em> = -4

<em>a b</em> = -2

Solve the second equation for <em>b</em> :

<em>b</em> = -2/<em>a</em>

Substitute this into the first equation:

<em>a</em> - 2/<em>a</em> = -4

Multiply both sides by <em>a</em> :

<em>a</em>² - 2 = -4<em>a</em>

Move 4<em>a</em> to the left side:

<em>a</em>² + 4<em>a</em> - 2 = 0

Use the quadratic formula to solve for <em>a</em> :

<em>a</em> = (-4 ± √(4² - 4(-2))) / 2

<em>a</em> = -2 ± √6

If <em>a</em> = -2 + √6, then

-2 + √6 + <em>b</em> = -4

<em>b</em> = -2 - √6

In the other case, we end up with the same numbers, but <em>a</em> and <em>b</em> are swapped.

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  • The margin of error of the proportion given is of 2.9%.
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The margin of error of a confidence interval of a proportion \pi in a sample of size n, with a confidence level of 1-\alpha, is:

M = z\sqrt{\frac{\pi(1-\pi)}{n}}

In which z is the z-score that has a p-value of 1 - \frac{\alpha}{2}.

The confidence interval is:

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In this problem:

  • Poll of 1012 people, thus n = 1012.
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95% confidence level

Thus \alpha = 0.05, z is the z-score that has a p-value of 1 - \frac{0.05}{2} = 0.975, so z = 1.96.  

The margin of error is:

M = 1.96\sqrt{\frac{0.32(0.68)}{1012}} = 0.029

As a percent, 2.9%, as 0.029 x 100% = 2.9%.

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32 - 2.9 = 29.1

32 + 2.9 = 34.9

The confidence interval is (29.1%, 34.9%).

A similar problem is given at brainly.com/question/16807970

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