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fiasKO [112]
3 years ago
15

Find the coordinates of the points of intersection of the graphs without building them: 5x–4y=16 and x–2y=6

Mathematics
1 answer:
Genrish500 [490]3 years ago
3 0

\bf \begin{cases} 5x-4y=16\\ \cline{1-1} x-2y=6\\ \boxed{x}=6+2y \end{cases}~\hspace{7em}\stackrel{\textit{substituting \underline{x} in the first equation}}{5\left( \boxed{6+2y} \right)-4y=16} \\\\\\ 30+10y-4y=16\implies 30+6y=16\implies 6y=-14 \\\\\\ y=-\cfrac{14}{6}\implies y=-\cfrac{7}{3}\implies \blacktriangleright y=-2\frac{1}{3} \blacktriangleleft \\\\[-0.35em] ~\dotfill

\bf \stackrel{\textit{since we know that}}{x=6+2y}\implies x=6+2\left( -\cfrac{7}{3} \right)\implies x=6+\left(-\cfrac{14}{3} \right) \\\\\\ x=6-\cfrac{14}{3}\implies x=\cfrac{18-14}{3}\implies x=\cfrac{4}{3}\implies \blacktriangleright x=1\frac{1}{3} \blacktriangleleft \\\\[-0.35em] \rule{34em}{0.25pt}\\\\ ~\hfill \left( 1\frac{1}{3} ~,~-2\frac{1}{3}\right)~\hfill

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Answer:

The 80% confidence interval for the mean number of toys purchased each year is between 7.5 and 7.7 toys.

Step-by-step explanation:

We have that to find our \alpha level, that is the subtraction of 1 by the confidence interval divided by 2. So:

\alpha = \frac{1 - 0.8}{2} = 0.1

Now, we have to find z in the Ztable as such z has a pvalue of 1 - \alpha.

That is z with a pvalue of 1 - 0.1 = 0.9, so Z = 1.28.

Now, find the margin of error M as such

M = z\frac{\sigma}{\sqrt{n}}

In which \sigma is the standard deviation of the population and n is the size of the sample.

M = 1.28\frac{1.5}{\sqrt{305}} = 0.1

The lower end of the interval is the sample mean subtracted by M. So it is 7.6 - 0.1 = 7.5

The upper end of the interval is the sample mean added to M. So it is 7.6 + 0.1 = 7.7

The 80% confidence interval for the mean number of toys purchased each year is between 7.5 and 7.7 toys.

8 0
3 years ago
Which of the following equations best models the data plotted below?
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The key with these problems is to find which function has the closest y-intercept to the graph, and then try to figure out which one best approximates the slope. 
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<span>A. y = x + 4 
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Which has the closest approximation of the slope? 
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6 0
2 years ago
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aleksandr82 [10.1K]

Answer:

c = -6

Step-by-step explanation:

To find the value of c to make the line pass through the point K = (2, -3), we just need to use the values of x = 2 and y = -3 in the equation, then we find the value of c.

So, we have that:

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To check if the value is correct, we can use the value x = 2 and see if the value of y is -3:

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3 years ago
Read 2 more answers
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Step-by-step explanation:

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