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what is the sum of the first 25 terms of an arithematic sequence if the sum of its 8th and 18th terms is 72?

max2010maxim [7]

Answer:

900

Step-by-step explanation:

7 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

I want to know the answer to the sum of f and 6

11111nata11111 [884]

f + 6 = ?

Well, the answer can be pretty much any number. It all depends on what number f is. f is a variable, so you can plug in any number to replace f.

For example, if f was 5, this is what the equation would look like:

5 + 6 = 11

If f was -3, this is what the equation would look like:

-3 + 6 = 3

So, again, the answer can be anything. It depends on what f is.

4 0

3 years ago

A researcher gathered data on hours of video games played by school-aged children and young adults. She collected the following

antiseptic1488 [7]

Step-by-step explanation:

The complete frequency distribution table for the data has been attached to this response.

The frequency column contains values that are the number of times the given range of hours appear in the data. For example, numbers in the range 0 - 2 hours, appear <em>9</em> times in the data. Also, the numbers in the range 3 - 5 appear <em>6</em> times. The same logic applies to other ranges.

The relative frequency column contains the ratio of the number of times the given range of hours appear in the data, to the total number of outcomes. The total number of outcomes is the sum of all the frequencies on the frequency column. This gives 38 as shown.

So, for example, to get the relative for the numbers in the range 0-2, divide their frequency (9) by the total outcome or frequency (38). i.e

9 / 38 = 0.24

Also, to get the relative for the numbers in the range 3-5, divide their frequency (6) by the total outcome or frequency (38). i.e

6 / 38 = 0.16

Do the same for the other ranges.

5 0

3 years ago

Thanks for the help number 11

jasenka [17]

Answer:

C

Step-by-step explanation:

6 0

3 years ago

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