Andrea earns $32.25 a day. After 9 days , about how much will she have earned?<br><br> ESTIMATE

A mortgage firm estimates the true mean current debt of local homeowners, using the current outstanding balance of a random samp

Nat2105 [25]

Answer:

b. Using the balances of 50 homeowners rather than 35, because using more data gives a smaller margin of error

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:

95% confidence interval

$\alpha = \frac{1-0.95}{2} = 0.025$

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

So it is z with a pvalue of $1-0.025 = 0.975$ , so $z = 1.96$

99% confidence interval

$\alpha = \frac{1-0.99}{2} = 0.005$

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

So it is z with a pvalue of $1-0.005 = 0.995$ , so $z = 2.575$

Now, find we find the width of our confidence interval M as such

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

So, as n increases, the width of the confidence interval decreases.

From the examples above, we can also conclude that as the confidence level increases, so does the value of z, which means that the width of the interval increases.

Which of the following would correctly produce a confidence interval with a smaller margin of error than this 95% confidence interval?

For a smaller margin of error, we need to have a bigger sample size.

So the correct answer is:

b. Using the balances of 50 homeowners rather than 35, because using more data gives a smaller margin of error

5 0

2 years ago

Will Mark brainiest!!!

NeTakaya

Answer:

b

Step-by-step explanation:

5 0

2 years ago

Read 2 more answers

A number n increased by 4 is -19

MrRa [10]

Answer:

n=23

Step-by-step explanation:

4-23=19

meme

6 0

3 years ago

Read 2 more answers

Find the x intercept. y = x + 3 / x - 2

VikaD [51]

Answer:

(-3, 0).

Step-by-step explanation:

At the x intercept y = 0 so

(x + 3) / (x - 2) = 0

x + 3 = 0

x = -3.

x-intercept is at (-3,0).

8 0

3 years ago

Calculate the sample mean and sample variance for the following frequency distribution of heart rates for a sample of American a

spin [16.1K]

Answer:

$Mean = 68.9$

$s^2 =18.1$ --- Variance

Step-by-step explanation:

Given

$\begin{array}{cccccc}{Class} & {51-58} & {59-66} & {67-74} & {75-82} & {83-90} \ \\ {Frequency} & {6} & {3} & {11} & {13} & {4} \ \end{array}$

Solving (a): Calculate the mean.

The given data is a grouped data. So, first we calculate the class midpoint (x)

For 51 - 58.

$x = \frac{1}{2}(51+58) = \frac{1}{2}(109) = 54.5$

For 59 - 66

$x = \frac{1}{2}(59+66) = \frac{1}{2}(125) = 62.5$

For 67 - 74

$x = \frac{1}{2}(67+74) = \frac{1}{2}(141) = 70.5$

For 75 - 82

$x = \frac{1}{2}(75+82) = \frac{1}{2}(157) = 78.5$

For 83 - 90

$x = \frac{1}{2}(83+90) = \frac{1}{2}(173) = 86.5$

So, the table becomes:

$\begin{array}{cccccc}{x} & {54.5} & {62.5} & {70.5} & {78.5} & {86.5} \ \\ {Frequency} & {6} & {3} & {11} & {13} & {4} \ \end{array}$

The mean is then calculated as:

$Mean = \frac{\sum fx}{\sum f}$

$Mean = \frac{54.5*4+62.5*3+70.5*11+78.5*13+86.5*4}{6+3+11+13+4}$

$Mean = \frac{2547.5}{37}$

$Mean = 68.9$ -- approximated

Solving (b): The sample variance:

This is calculated as:

$s^2 =\frac{\sum (x - \overline x)^2}{\sum f - 1}$

So, we have:

$s^2 =\frac{(54.5-68.9)^2+(62.5-68.9)^2+(70.5-68.9)^2+(78.5-68.9)^2+(86.5-68.9)^2}{37 - 1}$

$s^2 =\frac{652.8}{36}$

$s^2 =18.1$ -- approximated

5 0

2 years ago

Andrea earns $32.25 a day. After 9 days , about how much will she have earned? ESTIMATE