How many unique ways are there to arrange the letters in the word DEN?

What is the length (magnitude) of the vector (5,-2)?

kirill [66]

5^2+(-2)^2=29
magnitude=(29)^(1/2)=around 5.3852

3 0

4 years ago

The Rocky Mountain district sales manager of Rath Publishing Inc., a college textbook publishing company, claims that the sales

andrezito [222]

Answer:

$t=\frac{44-42}{\frac{1.9}{\sqrt{40}}}=6.657$

$p_v =P(t_{(39)}>6.657)=3.17x10^{-8}$

If we compare the p value and the significance level given $\alpha=0.01$ we see that $p_v$ so we can conclude that we have enough evidence to reject the null hypothesis, so we can conclude that the true mean is higher than 42 at 1% of signficance.

Step-by-step explanation:

Data given and notation

$\bar X=44$ represent the sample mean

$s=1.9$ represent the sample standard deviation

$n=40$ sample size

$\mu_o =42$ represent the value that we want to test

$\alpha=0.01$ represent the significance level for the hypothesis test.

t would represent the statistic (variable of interest)

$p_v$ represent the p value for the test (variable of interest)

State the null and alternative hypotheses.

We need to conduct a hypothesis in order to check if the mean is higher than 42, the system of hypothesis would be:

Null hypothesis: $\mu \leq 42$

Alternative hypothesis: $\mu > 42$

If we analyze the size for the sample is > 30 but we don't know the population deviation so is better apply a t test to compare the actual mean to the reference value, and the statistic is given by:

$t=\frac{\bar X-\mu_o}{\frac{s}{\sqrt{n}}}$ (1)

t-test: "Is used to compare group means. Is one of the most common tests and is used to determine if the mean is (higher, less or not equal) to an specified value".

Calculate the statistic

We can replace in formula (1) the info given like this:

$t=\frac{44-42}{\frac{1.9}{\sqrt{40}}}=6.657$

P-value

The first step is calculate the degrees of freedom, on this case:

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

Since is a one side test the p value would be:

$p_v =P(t_{(39)}>6.657)=3.17x10^{-8}$

Conclusion

If we compare the p value and the significance level given $\alpha=0.01$ we see that $p_v$ so we can conclude that we have enough evidence to reject the null hypothesis, so we can conclude that the true mean is higher than 42 at 1% of signficance.

3 0

3 years ago

a scientist from chile has transported volcanic ash samples to be tested in his lab if the scientist has 3540 grams of volcanic

Digiron [165]

3,540 grams of ash
If its density is 2.75 g/cc and
density = mass / volume then its volume is

volume = mass / density
volume = 3,540 g / 2.75 g / cc
volume = 1287.272727 cc
So, rounded it is 1,287.3 cubic centimeters but to keep the same number of significant figures, the volume is
volume = 1,287 cc

7 0

3 years ago

Factor completely: −4x2 + 16x − 24

mr_godi [17]

First, you need to see which number all of these numbers have in common, and that is number 4. So, let's start:

-4(x2 - 4x + 6)

The expression in the brackets cannot be factored further, which means that the answer above is the complete factor of the original expression. Hope it helps. :)

3 0

3 years ago

P and q are complex numbers such that ∣p∣ = 2/5 x + 2 , ∣q∣ = −3/4 x − 1 , and ∣p+q∣ = 2x + 4 .

Leya [2.2K]

Answer: (b)

Step-by-step explanation:

Given

$\left | p\right |=\dfrac{2}{5}x+2$

$\left | q\right |=\dfrac{-3}{4}x-1$

$\left | p+q\right |=2x+4$

for two complex number, $z_1,z_2$

Apply the above the property

$\Rightarrow 2x+4\leq \dfrac{2}{5}x+2-\dfrac{3}{4}x-1\\\\\Rightarrow 2x+4\leq \dfrac{8x-15x}{20}+1\\\\\Rightarrow 2x+3\leq -\dfrac{7x}{20}\\\Rightarrow x\leq -\dfrac{60}{47}$

Also, the absolute value of each complex number must be greater than or equal to zero

$\text{Case-1}\\\\\Rightarrow \dfrac{2}{5}x+2\geq 0\\\\\Rightarrow x\geq -5\\\\\text{Case-2}\\\\\Rightarrow -\dfrac{3}{4}x-1\geq 0\\\\\Rightarrow x\leq -\dfrac{4}{3}\\\\\text{Case-3}\\\\\Rightarrow 2x+4\geq 0\\\Rightarrow x\geq -2$

Taking the intersection of the above values of x, we get

$x\in [-2,-\dfrac{4}{3}]$

8 0

3 years ago