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svetoff [14.1K]
3 years ago
7

Without graphing ,find where each parabola crosses the x-axis.a) y=x^-2x-3

Mathematics
1 answer:
VMariaS [17]3 years ago
8 0
When the parabola crosses the x-axis the parabola "intersects" or touches the x-axis, and therefore is an x-intercept, and we can get those by simply setting y = 0 and getting "x".

\bf y=x^2-2x-3\implies \stackrel{y}{0}=x^2-2x-3\implies 0=(x-3)(x+1)
\\\\\\
x=
\begin{cases}
3\\
-1
\end{cases}
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Answer:

122 \leq \mu \leq 138

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And the correct interpretation for this case is:

c. If the procedure were repeated many times, 95% of the resulting confidence intervals would contain the population mean systolic blood pressure.

Step-by-step explanation:

Previous concepts

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % where by a population means lies between an upper and lower interval".  

The margin of error is the range of values below and above the sample statistic in a confidence interval.  

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Solution to the problem

The confidence interval for the mean is given by the following formula:  

\bar X \pm t_{\alpha/2}\frac{s}{\sqrt{n}} (1)  

In order to calculate the critical value t_{\alpha/2} we need to find first the degrees of freedom, given by:  

df=n-1=25-1=24  

Since the Confidence is 0.95 or 95%, the value of \alpha=0.05 and \alpha/2 =0.025, and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-T.INV(0.025,24)".And we see that t_{\alpha/2}=2.06  

Now we have everything in order to replace into formula (1), for this case we got:

122 \leq \mu \leq 138

The 95% confidence interval would be given by (122;138)

And the correct interpretation for this case is:

c. If the procedure were repeated many times, 95% of the resulting confidence intervals would contain the population mean systolic blood pressure.

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i just added em up

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Answer:

fourth option

Step-by-step explanation:

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