The answer is, 2/5 and 3/2
<span><span>2<span><span>(x+3)</span>2</span>+1</span><span>2<span><span>(x+3)</span>2</span>+1</span></span>Reorder the right side of the equation to match the vertex form of a parabola.<span><span>y=2<span><span>(x+3)</span>2</span>+1</span><span>y=2<span><span>(x+3)</span>2</span>+1</span></span>Use the vertex form, <span><span>y=a<span><span>(x−h)</span>2</span>+k</span><span>y=a<span><span>(x-h)</span>2</span>+k</span></span>, to determine the values of <span>aa</span>, <span>hh</span>, and <span>kk</span>.<span><span>a=2</span><span>a=2</span></span><span><span>h=−3</span><span>h=-3</span></span><span><span>k=1</span><span>k=1</span></span>Find the vertex <span><span>(h,k)</span><span>(h,k)</span></span>.<span>(−3,1<span>) ...................................</span></span>
Answer:
The 80% confidence interval for the mean per capita income in thousands of dollars is between $21.3 and $21.9.
Step-by-step explanation:
We have that to find our
level, that is the subtraction of 1 by the confidence interval divided by 2. So:

Now, we have to find z in the Ztable as such z has a pvalue of
.
So it is z with a pvalue of
, so 
Now, find the margin of error M as such

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

The lower end of the interval is the sample mean subtracted by M. So it is 21.6 - 0.3 = $21.3.
The upper end of the interval is the sample mean added to M. So it is 21.6 + 0.3 = $21.9.
The 80% confidence interval for the mean per capita income in thousands of dollars is between $21.3 and $21.9.