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3 years ago

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Of the 25 girls on the Alden Middle School soccer team, 40% also play on a travel team. How many of the girls on the middle scho

ol team also play on a travel team?

1 answer:

SpyIntel [72]3 years ago

5 0

Answer:

10 Girls

Step-by-step explanation:

Total number of girls in Alden Middle school= 25 girls

Percent of girls play for travel team= 40%

We have to find the numbers of girls who play for middle school team

Numbers of girls who play for middle school team= 25 × $\frac{40}{100}$

Numbers of girls who play for middle school team=25 × $\frac{40}{100}$

Numbers of girls who play for middle school team=10

Hence the number of girls play for travel team= 10 girls.

Hence, the correct answer is 10.

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My brother wants to estimate the proportion of Canadians who own their house.What sample size should be obtained if he wants the

AVprozaik [17]

Answer:

a) $n=\frac{0.675(1-0.675)}{(\frac{0.02}{1.64})^2}=1475.07$

And rounded up we have that n=1476

b) $n=\frac{0.5(1-0.5)}{(\frac{0.02}{1.64})^2}=1681$

And rounded up we have that n=1681

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".

The population proportion have the following distribution

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

The margin of error for the proportion interval is given by this formula:

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

If solve n from equation (a) we got:

$n=\frac{\hat p (1-\hat p)}{(\frac{ME}{z})^2}$ (b)

Part a

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 90% of confidence, our significance level would be given by $\alpha=1-0.9=0.1$ and $\alpha/2 =0.05$ . And the critical value would be given by:

$z_{\alpha/2}=\pm 1.64$

The margin of error for the proportion interval is given by this formula:

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

And on this case we have that $ME =\pm 0.02$ and we are interested in order to find the value of n, if we solve n from equation (a) we got:

$n=\frac{\hat p (1-\hat p)}{(\frac{ME}{z})^2}$ (b)

And replacing into equation (b) the values from part a we got:

$n=\frac{0.675(1-0.675)}{(\frac{0.02}{1.64})^2}=1475.07$

And rounded up we have that n=1476

Part b

For this case since we don't have a prior estimate we can use $\hat p =0.5$

$n=\frac{0.5(1-0.5)}{(\frac{0.02}{1.64})^2}=1681$

And rounded up we have that n=1681

8 0

3 years ago

The average price of a gallon of milk is $3.31. If the price increases .88% each year , how much will a gallon of milk cost in 2

musickatia [10]

Answer:

$3.94

Step-by-step explanation:

You will need to use the compound interest formula for this.

$P(1+\frac{r}{n} )^{nt}$

P = initial balance

r = interest rate

n = number of times compounded annually

t = time

Your equation will look like this:

$3.31(1+\frac{.0088}{1} )^{20}$ = 3.94

5 0

3 years ago

Simplify the following: 3(-3 + 5x) -1 (4 - 4x)

Gnesinka [82]

3(-3 + 5x) -1 (4 - 4x)

Simplify each term by first using the distributive property with each set of parenthesis:

3*-3 + 3*5x - 1*4 -1* -4x

Now do the multiplications:

-9 + 15x -4 + 4x

Combine like terms

15x +4x - 9 -4

19x - 13

8 0

3 years ago

A random sample of the costs of repair jobs at a large muffler repair shop produces a mean of $127.95. and a standard deviation

lubasha [3.4K]

Answer:

$127.95-1.685\frac{24.03}{\sqrt{40}}=121.55$

$127.95 +1.685\frac{24.03}{\sqrt{40}}=134.35$

So on this case the 90% confidence interval would be given by (121.55;134.35)

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".

$\bar X=127.95$ represent the sample mean for the sample

$\mu$ population mean (variable of interest)

s=24.03 represent the sample standard deviation

n represent the sample size

Solution to the problem

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

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

In order to calculate the critical value $t_{\alpha/2}$ we need to find first the degrees of freedom, given by:

$df=n-1=40-1=39$

Since the Confidence is 0.90 or 90%, the value of $\alpha=0.1$ and $\alpha/2 =0.05$ , and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-T.INV(0.05,39)".And we see that $t_{\alpha/2}=1.685$

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

$127.95-1.685\frac{24.03}{\sqrt{40}}=121.55$

$127.95 +1.685\frac{24.03}{\sqrt{40}}=134.35$

So on this case the 90% confidence interval would be given by (121.55;134.35)

8 0

3 years ago

Uh hey I really need help, thanks.

lana66690 [7]

Answer:

b. it's the same size

Step-by-step explanation:

7 0

3 years ago