Use reasoning algebra to write the unknown factor

A survey of 85 families showed that 36 owned at least one DVD player. Find the 99% confidence interval estimate of the true prop

attashe74 [19]

Answer:

$0.424 - 2.58\sqrt{\frac{0.424(1-0.424)}{85}}=0.286$

$0.424 + 2.58\sqrt{\frac{0.424(1-0.424)}{85}}=0.562$

The 99% confidence interval would be given by (0.286;0.562)

Step-by-step explanation:

Information given:

$X= 36$ represent the families owned at least one DVD player

$n= 85$ represent the total number of families

$\hat p=\frac{36}{85}= 0.424$ represent the estimated proportion of families owned at least one DVD player

In order to find the critical value we need to take in count that we are finding the interval for a proportion, so on this case we need to use the z distribution. Since our interval is at 99% of confidence, our significance level would be given by $\alpha=1-0.99=0.01$ and $\alpha/2 =0.05$ . And the critical value would be given by:

$z_{\alpha/2}=-2.58, z_{1-\alpha/2}=2.58$

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

$\hat p \pm z_{\alpha/2}\sqrt{\frac{\hat p (1-\hat p)}{n}}$

If we replace the values obtained we got:

$0.424 - 2.58\sqrt{\frac{0.424(1-0.424)}{85}}=0.286$

$0.424 + 2.58\sqrt{\frac{0.424(1-0.424)}{85}}=0.562$

The 99% confidence interval would be given by (0.286;0.562)

8 0

3 years ago

Graph y=x+1/x² and y=1/x for positive values of x.

AlekseyPX

Answer:

Graphic is showed in the figure below

Step-by-step explanation:

To graph the equations given, let's do a table for positive values of x, and, by replacing it in the equation, let's calculate the value of y. Knowing the coordinate points (x,y) we can build the graphic.

1 2 1

2 2.25 0.2

3 3.11 0.33

4 4.06 0.25

When x->0 both equations -> ∞, because lim(1/x) x->0 = ∞

The graphic is showed below. In red there is y = 1 + 1/x² and in blue y = 1/x