The radius of the circle above is 7 in. What is the circumference of the circle? (Use = 3.14)

Greeley [361]

Yes, it is. To find this out, you need to make the denominators the same. They can both multiply into 15, so we change the denominators to 15. Whatever we do to the bottom, we also have to do to the top.

2/3 = 10/15

1/5 = 3/15

We can then see that 10 is more than 3 :)

8 0

3 years ago

A Pew Internet poll asked cell phone owners about how they used their cell phones. One question asked whether or not during the

EastWind [94]

Answer:

a) $\hat p=\frac{471}{1024}=0.460$

The standard error is given by:

$SE= \sqrt{\frac{\hat p(1-\hat p)}{n}}=\sqrt{\frac{0.460(1-0.460)}{1024}}=0.0156$

And the margin of error is given by:

$ME=z_{\alpha/2} \sqrt{\frac{\hat p(1-\hat p)}{n}}=1.96\sqrt{\frac{0.460(1-0.460)}{1024}}=0.0305$

b) The 99% confidence interval would be given by (0.429;0.491)

Step-by-step explanation:

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 % whereby 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.

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

The population proportion have the following distribution

$p \sim N(p,\sqrt{\frac{p(1-p)}{n}})$

Data given and notation

n=1024 represent the random sample taken

X=471 represent the people responded that they had used their cell phone while in a store within the last 30 days to call a friend or family member for advice about a purchase they were considering

$\hat p=\frac{471}{1024}=0.460$ estimated proportion of people responded that they had used their cell phone while in a store within the last 30 days to call a friend or family member for advice about a purchase they were considering

p= population proportion of people responded that they had used their cell phone while in a store within the last 30 days to call a friend or family member for advice about a purchase they were considering

Part a

The confidence interval would be given by this formula

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

For the 95% confidence interval the value of $\alpha=1-0.95=0.05$ and $\alpha/2=0.025$ , with that value we can find the quantile required for the interval in the normal standard distribution.

$z_{\alpha/2}=1.96$

The standard error is given by:

$SE= \sqrt{\frac{\hat p(1-\hat p)}{n}}=\sqrt{\frac{0.460(1-0.460)}{1024}}=0.0156$

And the margin of error is given by:

$ME=z_{\alpha/2} \sqrt{\frac{\hat p(1-\hat p)}{n}}=1.96\sqrt{\frac{0.460(1-0.460)}{1024}}=0.0305$

Part b

If we replace the values obtained we got:

$0.460-1.96\sqrt{\frac{0.460(1-0.460)}{1024}}=0.429$

$0.460+1.96\sqrt{\frac{0.460(1-0.460)}{1024}}=0.491$

The 99% confidence interval would be given by (0.429;0.491)

8 0

3 years ago

Which value, when placed in the box, would result in a system of equations with infinitely many solutions? y = -2x 4 6x 3y =

wariber [46]

The missing value is 12 in a system of equations with infinitely many solutions conditions.

It is given that in the system of equations there are two equations given:

$\rm y =n -2x+4\\\rm and \\\rm 6x+3y= ?$

It is required to find the missing value in the second equation.

<h3>What is a linear equation?</h3>

It is defined as the relation between two variables if we plot the graph of the linear equation we will get a straight line.

We have equations:

$\rm y = -2x+4 ....(1)\\ \\\rm 6x+3y= ? ....(2)$

Let's suppose the missing value is 'Z'

We know that the two pairs of equations have infinitely many solutions if and if they have the same coefficients of variables and the same constant on both sides.

From equation (1)

$\rm y = -2x+4 \\\\\rm 2x+y=4$ (multiply both the sides by 3)