33% X$90 rounded up to thr next highest dollar minus one cent

Math help plz! Check for extraneous solutions. Giving brainlist

Dima020 [189]

This is number 8. the second person got number 9

4 0

3 years ago

<img src="https://tex.z-dn.net/?f=%20%5Crm%20%5Cint_%7B0%7D%5E%7B%20%20%5Cpi%20%7D%20%5Ccos%28%20%5Ccot%28x%29%20%20%20%20-%20%2

Nikolay [14]

Replace x with π/2 - x to get the equivalent integral

$\displaystyle \int_{-\frac\pi2}^{\frac\pi2} \cos(\cot(x) - \tan(x)) \, dx$

but the integrand is even, so this is really just

$\displaystyle 2 \int_0^{\frac\pi2} \cos(\cot(x) - \tan(x)) \, dx$

Substitute x = 1/2 arccot(u/2), which transforms the integral to

$\displaystyle 2 \int_{-\infty}^\infty \frac{\cos(u)}{u^2+4} \, du$

There are lots of ways to compute this. What I did was to consider the complex contour integral

$\displaystyle \int_\gamma \frac{e^{iz}}{z^2+4} \, dz$

where γ is a semicircle in the complex plane with its diameter joining (-R, 0) and (R, 0) on the real axis. A bound for the integral over the arc of the circle is estimated to be

$\displaystyle \left|\int_{z=Re^{i0}}^{z=Re^{i\pi}} f(z) \, dz\right| \le \frac{\pi R}{|R^2-4|}$

which vanishes as R goes to ∞. Then by the residue theorem, we have in the limit

$\displaystyle \int_{-\infty}^\infty \frac{\cos(x)}{x^2+4} \, dx = 2\pi i {} \mathrm{Res}\left(\frac{e^{iz}}{z^2+4},z=2i\right) = \frac\pi{2e^2}$

and it follows that

$\displaystyle \int_0^\pi \cos(\cot(x)-\tan(x)) \, dx = \boxed{\frac\pi{e^2}}$

7 0

2 years ago

A researcher working in a Human Resources department was interested in gender and sales figures so he conducted a t-test. The me

irina1246 [14]

Answer:

$d = \frac{78.24 -66.25}{\sqrt{\frac{7^2 +7^2}{2}}}= 1.713$

For the interpretation we consider a value for d small is is between 0-0.2, medium if is between 0.2-0.8 and large if is higher than 0.8.

And on this case 1.713>0.8 so we have a large effect size

This value of d=1.713 are telling to us that the two groups differ by 1.713 standard deviation and we will have a significant difference between the two means.

Step-by-step explanation:

Previous concepts

The Effect size is a "quantitative measure of the magnitude of the experimenter effect. "

The Cohen's d effect size is given by the following formula:

$d = \frac{\bar X_1 -\bar X_2}{\sqrt{\frac{s^2_1 +s^2_2}{2}}}$

Solution to the problem

And for this case we can assume:

$\bar X_1 =78.24$ the mean for females

$\bar X_2 =66.25$ the mean for males

$s_1 = s_2= 7$ represent the deviations for both groups

And if we replace we got:

$d = \frac{78.24 -66.25}{\sqrt{\frac{7^2 +7^2}{2}}}= 1.713$

For the interpretation we consider a value for d small is is between 0-0.2, medium if is between 0.2-0.8 and large if is higher than 0.8.

And on this case 1.713>0.8 so we have a large effect size

This value of d=1.713 are telling to us that the two groups differ by 1.713 standard deviation and we will have a significant difference between the two means.

4 0

2 years ago

I need help with these two answers please :/

4vir4ik [10]