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2 years ago

Which is the pattern for factoring the sum of cubes

Mathematics

2 answers:

vovikov84 [41]2 years ago

4 0

Answer: Its B

Step-by-step explanation: trust me i had this test

Stels [109]2 years ago

3 0

Answer:

4th option

Step-by-step explanation:

The factors of a³ + b³ are

a³ + b³ = (a + b)(a² - ab + b² )

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The homoskedasticity-only F-statistic and the heteroskedasticity-robust F-statistic typically are:

LiRa [457]

Answer:

The homoskedasticity-only F-statistic and the heteroskedasticity-robust F-statistic typically are different.

Step-by-step explanation:

An F statistic is a value derived by running an ANOVA test or a regression analysis to find out if the means between two populations are significantly different.

The homoskedasticity-only” F-statistic is derived by running two regressions, one under the null hypothesis and one under the alternative hypothesis. If the “unrestricted” model fits sufficiently better, reject the null.

In the first regression, the restricted regression (the null hypothesis) is forced to be true. This is the regression in which all the coefficients are set to zero; the relevant regressors are excluded from the regression. In the second regression, the unrestricted regression, the alternative hypothesis is allowed to be true. If the sum of squared residuals is sufficiently smaller in the unrestricted than the restricted regression, then the test rejects the null hypothesis

The heteroskedasticity-robust F-statistic is built in to STATA (“test” command); this tests all q restrictions at once.

The homoskedasticity-only F-statistic is important historically (and also in practice), and can help intuition, but isn’t valid when there is heteroskedasticity

6 0

2 years ago

Melissa has three different positive integers. She adds their reciprocals together and gets a sum of $1$. What is the product of

Whitepunk [10]

If the three integers are $a,b,c$ , then we have

$\dfrac1a+\dfrac1b+\dfrac1c=1$

We can combine the fractions on the left side:

$\dfrac{bc}{abc}+\dfrac{ac}{abc}+\dfrac{ab}{abc}=\dfrac{bc+ac+ab}{abc}=1$

$\implies abc=bc+ac+ab$

4 0

2 years ago

Read 2 more answers

In a given quadrilateral, each side is parallel to its opposite side and the diagonals are not perpendicular. What could it be?

Assoli18 [71]

Answer
A. Rectangle
D. Parallelogram

Explanation
The four choices are all quadrilaterals with with at least a pair of parallel sides.
A rectangle, a square, and a rhombus have opposite sides been parallel.
For a square and a rhombus, the diagonals are perpendicular.

The diagonals of a rectangle and a parallelograms are not perpendicular.

5 0

2 years ago

Read 2 more answers

Let μ1 and μ2 denote true average densities for two different types of brick. Assuming normality of the two density distribution

Nuetrik [128]

Answer:

a) $df= \frac{(\frac{0.161^2}{8} +\frac{0.25^2}{6})^2}{\frac{1}{8 -1} (\frac{0.161^2}{8})^2 +\frac{1}{6 -1} (\frac{0.25^2}{6})^2} = 8.03 \ approx 8$

b) $t=\frac{24.74-20.92}{\sqrt{\frac{0.161^2}{8}+\frac{0.25^2}{6}}}=32.688$

$p_v = 2*P(t_{8}>32.688)= 4.18x10^{-9}$

c) $ME= 2.306 \sqrt{\frac{0.161^2}{8}+\frac{0.25^2}{6}}= 0.269$

Step-by-step explanation:

Part a

For this case the satterthwaite approximation is given by:

$df= \frac{(\frac{s^2_1}{n_1} +\frac{s^2_2}{n_2})^2}{\frac{1}{n_1 -1} (\frac{s^2_1}{n_1})^2 +\frac{1}{n_2 -1} (\frac{s^2_2}{n_2})^2}$

And if we replace we got:

$df= \frac{(\frac{0.161^2}{8} +\frac{0.25^2}{6})^2}{\frac{1}{8 -1} (\frac{0.161^2}{8})^2 +\frac{1}{6 -1} (\frac{0.25^2}{6})^2} = 8.03 \ approx 8$

Part b

Data given and notation

$\bar X_{1}=24.74$ represent the mean for 1

$\bar X_{2}=20.92$ represent the mean for 2

$s_{1}=0.161$ represent the sample standard deviation for 1

$s_{2}=0.25$ represent the sample standard deviation for 2

$n_{1}=8$ sample size for 1

$n_{2}=6$ sample size for 2

t would represent the statistic (variable of interest)

$p_v$ represent the p value

Concepts and formulas to use

We need to conduct a hypothesis in order to check if the mean for men it's higher than the mean for women, the system of hypothesis would be:

H0: $\mu_{1} = \mu_{2}$

H1: $\mu_{1} \neq \mu_{2}$

If we analyze the size for the samples both are lower than 30, and we don't know the population deviation's, so for this case is better apply a t test to compare means, and the statistic is given by:

$t=\frac{\bar X_{1}-\bar X_{2}}{\sqrt{\frac{s^2_{1}}{n_{1}}+\frac{s^2_{2}}{n_{2}}}}$ (1)

T-test: Is used to compare group means. Is one of the most common tests and is used to determine whether the means of two groups are equal to each other.

Calculate the statistic

We have all in order to replace in formula (1) like this:

$t=\frac{24.74-20.92}{\sqrt{\frac{0.161^2}{8}+\frac{0.25^2}{6}}}=32.688$

P value

For this case since we have a bilateral test and since we know the degrees of freedom calculated form part a we can find the p value like this:

$p_v = 2*P(t_{8}>32.688)= 4.18x10^{-9}$

And since the $p_v < \alpha$ we have enough evidence to reject the null hypothesis at 5% of significance.

Part c

The margin of error for this case is given by:

$ME= t_{\alpha/2} \sqrt{\frac{s^2_{1}}{n_{1}}+\frac{s^2_{2}}{n_{2}}}$

We can find the critical value with the following excel formula:

"-=T.INV(0.025;8)"

$t_{\alpha/2}= 2.306$

And if we replace we got:

$ME= 2.306 \sqrt{\frac{0.161^2}{8}+\frac{0.25^2}{6}}= 0.269$

3 0

2 years ago

Luke’s soccer team won 12 games and lost 5 games. Select all the expressions that show the ratio of wins to losses. Asap plz

almond37 [142]

Answer:

We don't have any options to choose from, but here are some general ones:

12:5

12 / 5

41% of games Luke lost.

59% of games Luke won.

Step-by-step explanation:

4 0

2 years ago

Which is the pattern for factoring the sum of cubes​

Which is the pattern for factoring the sum of cubes