20% a number is 6. Determine the value of the number

Of the 725 students at Franklin Middle School, 12/25 play a sport. How many students play a sport at Franklin Middle School?

Paladinen [302]

Answer:

348 out of 725

Step-by-step explanation:

This is a ratio question, giving us a sample that we can use to extend the number to all students.

12/25 students play a sport so we want the value of x in x/725

So:

12/25 = x/725

Cross-Multiply:

25x = 8700

Divide by 25 to get x:

348

You can also check by dividing these ratios to see if you get the same number. In this case, you do (.48).

8 0

3 years ago

An SRS of 350 high school seniors gained an average of x¯=21 points in their second attempt at the SAT Mathematics exam. Assume

Lynna [10]

Answer:

a) $21-2.58\frac{52}{\sqrt{350}}=13.83$

$21+2.58\frac{52}{\sqrt{350}}=28.17$

So on this case the 99% confidence interval would be given by (13.83;28.17)

b) $ME=2.58\frac{52}{\sqrt{350}}=7.17$

c) $ME=2.58\frac{52}{\sqrt{100}}=13.42$

d) D. Decreasing the sample size increases the margin of error, provided the confidence level and population standard deviation remain the same.

Step-by-step explanation:

Previous concepts

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".

Part a

$\bar X=21$ represent the sample mean

$\mu$ population mean (variable of interest)

$\sigma=52$ represent the population standard deviation

n=350 represent the sample size

99% confidence interval

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

$\bar X \pm z_{\alpha/2}\frac{\sigma}{\sqrt{n}}$ (1)

Since the Confidence is 0.99 or 99%, the value of $\alpha=0.01$ and $\alpha/2 =0.005$ , and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-NORM.INV(0.005,0,1)".And we see that $z_{\alpha/2}=2.58$

Now we have everything in order to replace into formula (1):

$21-2.58\frac{52}{\sqrt{350}}=13.83$

$21+2.58\frac{52}{\sqrt{350}}=28.17$

So on this case the 99% confidence interval would be given by (13.83;28.17)

Part b

The margin of error is given by:

$ME=2.58\frac{52}{\sqrt{350}}=7.17$

Part c

The margin of error is given by:

$ME=2.58\frac{52}{\sqrt{100}}=13.42$

Part d

As we can see when we reduce the sample size we increase the margin of error so the best option for this case is:

D. Decreasing the sample size increases the margin of error, provided the confidence level and population standard deviation remain the same.

6 0

3 years ago

What minus 9 equals 11

Naddika [18.5K]

Answer:

20

Step-by-step explanation:

20 - 9 = 11

I hope this helps

6 0

3 years ago

Read 2 more answers

Micah is buying candy for the Halloween party. There will be 13 adults and

emmainna [20.7K]

Micah will need to buy 7 packages.

13 x 3 = 39
39 + 17 = 56
56 / 8 = 7

Hope this helps :)

3 0

3 years ago

The center is a typical value. It is the _______________ value of a dot plot.

larisa [96]

When referring to a dot plot, scatter graph, or scatter plot such as this one, the line that represents the averages of all Y values is known as a line of best fit.

Hope this helps,

Jeron

:)

6 0

2 years ago

Read 2 more answers