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3 years ago

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Catherine paid $185.30 for an MP3 player. If the price paid includes a 9% sales tax, which of the following equations can be use

d to determine the price of the MP3 Player before tax? (Let x represent the cost of the MP3 player and y represent the total cost after tax.)

1 answer:

Wittaler [7]3 years ago

8 0

y = $185.30

x = the orignal cost minus 9% or .09. To increase an objects value by 9% you need to multiply by 1 + .09 or 1.09. So, x being increases by 9% would equal y or $185.30

1.09x = y

1.09x = $185.30

Divide both sides by 1.09

x = $170

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The correct answer is the first choice, ($1818.30, $5077.70.)

To find this, we first find the z-score based on the confidence level:
Convert 95% to a decimal: 95%=95/100 = 0.95
Subtract from 1: 1-0.95 = 0.05
Divide by 2: 0.05/2 = 0.025
Subtract from 1: 1-0.025 = 0.975

Using a z-table (http://www.z-table.com) we see that this value is associated with a z-score of 1.96.

Next, we identify
$\overline{x_1}=39902; \overline{x_2}=36454; n_1=74; n_2=40; \sigma_1=3270; \sigma_2=4677$

Next we find
$(\overline{x_1}-\overline{x_2})=(39902-36454) = 3448$

Next we find
$\sqrt{\frac{\sigma_1^2}{n_1}+\frac{\sigma_2^2}{n_2}}
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\\=\sqrt{\frac{3270^2}{74}+\frac{4677^2}{40}}=\sqrt{\frac{10692900}{74}+\frac{21874329}{40}}
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How do i solve that question?

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a) The solution of this <em>ordinary</em> differential equation is $y =\sqrt[3]{-\frac{2}{\frac{3\cdot t}{8}-\frac{\sin 2t}{4}+\frac{\sin 4t}{32}-2 } }$ .

b) The integrating factor for the <em>ordinary</em> differential equation is $-\frac{1}{x}$ .

The <em>particular</em> solution of the <em>ordinary</em> differential equation is $y = \frac{x^{3}}{2}+x^{2}-\frac{5}{2}$ .

<h3>How to solve ordinary differential equations</h3>

a) In this case we need to separate each variable ( $y, t$ ) in each side of the identity:

$6\cdot \frac{dy}{dt} = y^{4}\cdot \sin^{4} t$ (1)

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The solution of this <em>ordinary</em> differential equation is $y =\sqrt[3]{-\frac{2}{\frac{3\cdot t}{8}-\frac{\sin 2t}{4}+\frac{\sin 4t}{32}-2 } }$ . $\blacksquare$

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The solution for (2) is presented below:

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Where $C$ is the integration constant.

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