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3 years ago

What is 2x3-4x5 and 3x6=

Mathematics

1 answer:

lukranit [14]3 years ago

3 0

Answer:

4 I believe

Step-by-step explanation:

sorry if im wrong, (didn't know if the and was to add or multiply,sorry!)

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Round 2,212,682 to the nearest thousand

Artist 52 [7]

2,213,000, 6 is closer to 10 than 0.

5 0

3 years ago

In Marissa's calculus course, attendance counts for 15% of the grade, quizzes count for 20% of the grade, exams count for

Alexandra [31]

Answer:

Her average was 87.35% on this course.

Step-by-step explanation:

In order to determine Marissa's average we need to take the average she has on each of the cattegories and find how much that relates to the weight of the cattegory on the final grade. We have:

Attendance counts for 15% of the grade and she has 100% average on that. So we have:

attendance = weight*(Marissa's average)

attendance = 15%*(100/100) = 15%

Quizzes counts for 20% of the grade and she has a 93% average on that. So we have:

Quizzes = weigth*(Marissa's average)

Quizzes = 20%*(93/100) = 18.6 %

Exams counts for 50% of the grade and she has a 82% average on that. So we have:

Exams = weigth*(Marissa's average)

Exams = 50%*(82/100) = 41%

The final exam counts for 15% of the grade and she has a average of 85% on that so we have:

Finals = 15%*(85/100) = 12.75%

So her grade is the sum of all the cattegories:

Course's average = 15+18.6+41+12.75 = 87.35 %

4 0

3 years ago

Read 2 more answers

Can someone help me please??

dem82 [27]

Add all the sides together
10+15+7+8+8+2=50 ft

7 0

2 years ago

Read 2 more answers

The lifetime X (in hundreds of hours) of a certain type of vacuum tube has a Weibull distribution with parameters α = 2 and β =

stich3 [128]

I'm assuming $\alpha$ is the shape parameter and $\beta$ is the scale parameter. Then the PDF is

$f_X(x)=\begin{cases}\dfrac29xe^{-x^2/9}&\text{for }x\ge0\\\\0&\text{otherwise}\end{cases}$

a. The expectation is

$E[X]=\displaystyle\int_{-\infty}^\infty xf_X(x)\,\mathrm dx=\frac29\int_0^\infty x^2e^{-x^2/9}\,\mathrm dx$

To compute this integral, recall the definition of the Gamma function,

$\Gamma(x)=\displaystyle\int_0^\infty t^{x-1}e^{-t}\,\mathrm dt$

For this particular integral, first integrate by parts, taking

$u=x\implies\mathrm du=\mathrm dx$

$\mathrm dv=xe^{-x^2/9}\,\mathrm dx\implies v=-\dfrac92e^{-x^2/9}$

$E[X]=\displaystyle-xe^{-x^2/9}\bigg|_0^\infty+\int_0^\infty e^{-x^2/9}\,\mathrm x$

$E[X]=\displaystyle\int_0^\infty e^{-x^2/9}\,\mathrm dx$

Substitute $x=3y^{1/2}$ , so that $\mathrm dx=\dfrac32y^{-1/2}\,\mathrm dy$ :

$E[X]=\displaystyle\frac32\int_0^\infty y^{-1/2}e^{-y}\,\mathrm dy$

$\boxed{E[X]=\dfrac32\Gamma\left(\dfrac12\right)=\dfrac{3\sqrt\pi}2\approx2.659}$

The variance is

$\mathrm{Var}[X]=E[(X-E[X])^2]=E[X^2-2XE[X]+E[X]^2]=E[X^2]-E[X]^2$

The second moment is

$E[X^2]=\displaystyle\int_{-\infty}^\infty x^2f_X(x)\,\mathrm dx=\frac29\int_0^\infty x^3e^{-x^2/9}\,\mathrm dx$

Integrate by parts, taking

$u=x^2\implies\mathrm du=2x\,\mathrm dx$

$\mathrm dv=xe^{-x^2/9}\,\mathrm dx\implies v=-\dfrac92e^{-x^2/9}$

$E[X^2]=\displaystyle-x^2e^{-x^2/9}\bigg|_0^\infty+2\int_0^\infty xe^{-x^2/9}\,\mathrm dx$

$E[X^2]=\displaystyle2\int_0^\infty xe^{-x^2/9}\,\mathrm dx$

Substitute $x=3y^{1/2}$ again to get

$E[X^2]=\displaystyle9\int_0^\infty e^{-y}\,\mathrm dy=9$

Then the variance is

$\mathrm{Var}[X]=9-E[X]^2$

$\boxed{\mathrm{Var}[X]=9-\dfrac94\pi\approx1.931}$

b. The probability that $X\le3$ is

$P(X\le 3)=\displaystyle\int_{-\infty}^3f_X(x)\,\mathrm dx=\frac29\int_0^3xe^{-x^2/9}\,\mathrm dx$

which can be handled with the same substitution used in part (a). We get

$\boxed{P(X\le 3)=\dfrac{e-1}e\approx0.632}$

c. Same procedure as in (b). We have

$P(1\le X\le3)=P(X\le3)-P(X\le1)$

and

$P(X\le1)=\displaystyle\int_{-\infty}^1f_X(x)\,\mathrm dx=\frac29\int_0^1xe^{-x^2/9}\,\mathrm dx=\frac{e^{1/9}-1}{e^{1/9}}$

Then

$\boxed{P(1\le X\le3)=\dfrac{e^{8/9}-1}e\approx0.527}$

7 0

2 years ago

Can you guy help for this questing <br> 1234

postnew [5]

Answer:

1. Median

2. Altitude

3. Altitude

4. Neither

Step-by-step explanation:

Median- splits the side into two congruent parts

Altitude- Makes a right angle

1. Splits the side. Median

2. Makes a right angle. Altitude

3. Makes a right angle. Altitude

4. Doesn't make a right angle or split the sides. Neither

4 0

2 years ago