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3 years ago

Brainliest and Five Stars for correct answers

1 answer:

wel3 years ago

3 0

$\bf \lim\limits_{x\to 9}~\cfrac{x^2-81}{x-9}\implies \cfrac{\stackrel{\textit{difference of squares}}{x^2-9^2}}{x-9}\implies \cfrac{\underline{(x-9)}(x+9)}{\underline{(x-9)}}
\\\\\\
\lim\limits_{x\to 9}~x+9\implies (9)+9\implies 18$

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Look at the image below.

tatuchka [14]

Answer:

add all the sides up

Step-by-step explanation:

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3 years ago

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A news article says that high school students are currently spending an average of 15 hours per week doing homework online. You

Wewaii [24]

Answer:

Step-by-step explanation:

The null hypothesis is the hypothesis that is assumed to be true. It is an expression that is the opposite of what the researcher predicts.

The alternative hypothesis is what the researcher expects or predicts. It is the statement that is believed to be true if the null hypothesis is rejected.

From the given situation,

news article says that high school students are currently spending an average of 15 hours per week doing homework online. This is the null hypothesis.

H0: µ = 15 hours

You don't think this is an accurate estimate, although you're not sure whether the real value is higher or lower. This is the alternative hypothesis.

Ha : µ ≠ 15 hours

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3 years ago

Fx = 6x and gx = 4x+ 1 find (fog)x

kumpel [21]

(fg)x = f(g(x)) = 6(4x+1) = 24x + 6

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3 years ago

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For each bracelet Julie makes, SHES uses 5 green beads, 6 red beads, and 7 white beads, how many bracelets can she make?

Masteriza [31]

Answer:

d; 151 bracelets

Step-by-step explanation:

to find this out we must divide each number of beads by their matching color amounts

1012 / 5 is 202.4 or 202

998 / 6 is 164.6... or 164

1057 / 7 is 151

151 is the least number out of all of these and in this case you can only make 151 bracelets or else you would run out of white

6 0

2 years ago

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A sample of 200 observations from the first population indicated that X1 is 170. A sam- ple of 150 observations from the second

nikitadnepr [17]

Answer:

a. If the P-value is smaller than the significance level, the null hypothesis is rejected.

b. Pooled proportion = 0.8

c. z = 2.7

d. As the P-value (0.0072) is smaller than the significance level (0.05), the null hypothesis is rejected.

There is enough evidence to support the claim that the proportions differ significantly.

Step-by-step explanation:

This is a hypothesis test for the difference between proportions.

We will use the P-value approach, so the decision rule is that if the P-value is lower than the significance level, the null hypothesis is rejected.

The claim is that the proportions differ significantly.

Then, the null and alternative hypothesis are:

$H_0: \pi_1-\pi_2=0\\\\H_a:\pi_1-\pi_2\neq 0$

The significance level is 0.05.

The sample 1, of size n1=200 has a proportion of p1=0.85.

$p_1=X_1/n_1=170/200=0.85$

The sample 2, of size n2=150 has a proportion of p2=0.7333.

$p_2=X_2/n_2=110/150=0.7333$

The difference between proportions is (p1-p2)=0.1167.

$p_d=p_1-p_2=0.85-0.7333=0.1167$

The pooled proportion, needed to calculate the standard error, is:

$p=\dfrac{X_1+X_2}{n_1+n_2}=\dfrac{170+110}{200+150}=\dfrac{280}{350}=0.8$

The estimated standard error of the difference between means is computed using the formula:

$s_{p1-p2}=\sqrt{\dfrac{p(1-p)}{n_1}+\dfrac{p(1-p)}{n_2}}=\sqrt{\dfrac{0.8*0.2}{200}+\dfrac{0.8*0.2}{150}}\\\\\\s_{p1-p2}=\sqrt{0.0008+0.00107}=\sqrt{0.00187}=0.0432$

Then, we can calculate the z-statistic as:

$z=\dfrac{p_d-(\pi_1-\pi_2)}{s_{p1-p2}}=\dfrac{0.1167-0}{0.0432}=\dfrac{0.1167}{0.0432}=2.7$

This test is a two-tailed test, so the P-value for this test is calculated as (using a z-table):

$P-value=2\cdot P(z>2.7)=0.0072$

As the P-value (0.0072) is smaller than the significance level (0.05), the effect is significant.

The null hypothesis is rejected.

There is enough evidence to support the claim that the proportions differ significantly.

6 0

3 years ago