A number is divided into the ratio 5:9. If the first part is 35, find the number.

Suppose that Y has density function

zvonat [6]

I'm assuming

$f(y)=\begin{cases}ky(1-y)&\text{for }0\le y\le1\\0&\text{otherwise}\end{cases}$

(a) f(x) is a valid probability density function if its integral over the support is 1:

$\displaystyle\int_{-\infty}^\infty f(x)\,\mathrm dx=k\int_0^1 y(1-y)\,\mathrm dy=k\int_0^1(y-y^2)\,\mathrm dy=1$

Compute the integral:

$\displaystyle\int_0^1(y-y^2)\,\mathrm dy=\left(\frac{y^2}2-\frac{y^3}3\right)\bigg|_0^1=\frac12-\frac13=\frac16$

So we have

k / 6 = 1 → k = 6

(b) By definition of conditional probability,

P(Y ≤ 0.4 | Y ≤ 0.8) = P(Y ≤ 0.4 and Y ≤ 0.8) / P(Y ≤ 0.8)

P(Y ≤ 0.4 | Y ≤ 0.8) = P(Y ≤ 0.4) / P(Y ≤ 0.8)

It makes sense to derive the cumulative distribution function (CDF) for the rest of the problem, since F(y) = P(Y ≤ y).

We have

$\displaystyle F(y)=\int_{-\infty}^y f(t)\,\mathrm dt=\int_0^y6t(1-t)\,\mathrm dt=\begin{cases}0&\text{for }y$

Then

P(Y ≤ 0.4) = F (0.4) = 0.352

P(Y ≤ 0.8) = F (0.8) = 0.896

and so

P(Y ≤ 0.4 | Y ≤ 0.8) = 0.352 / 0.896 ≈ 0.393

(c) The 0.95 quantile is the value φ such that

P(Y ≤ φ) = 0.95

In terms of the integral definition of the CDF, we have solve for φ such that

$\displaystyle\int_{-\infty}^\varphi f(y)\,\mathrm dy=0.95$

We have

$\displaystyle\int_{-\infty}^\varphi f(y)\,\mathrm dy=\int_0^\varphi 6y(1-y)\,\mathrm dy=(3y^2-2y^3)\bigg|_0^\varphi = 0.95$

which reduces to the cubic

3φ² - 2φ³ = 0.95

Use a calculator to solve this and find that φ ≈ 0.865.

8 0

2 years ago

What are the measures of Angles a, b, and c? Show your work and explain your

kobusy [5.1K]

Answer:

a= 30

b=60

c=105

Step-by-step explanation:

A forms a vertical angle with another angle that measures 30 degrees, therefore,

a= 30 degrees.

Since a is 30 degrees and a and b are in the same triangle with a 90-degree angle and all interior angles in a triangle equal 180 degrees.

Then, 30+90+b=180

120+b=180

b=60

Angle c and an angle that equals 75 degrees are supplementary. meaning that they add up to 180 degrees.

180-75=c

105=c

3 0

1 year ago

Sheree’s brother gave samuel his collection of stamps when she left for college. at that time, the value of the collection was $

AlekseyPX

The rate of change of stamp collection was $57.5 per year.

Rate is comparison of two related quantities.

Often the second quantity is time (per second, per hour, etc) but it can be anything.

Can be in the style "this per that" or as a single number calculated using division.

Example: Sam makes 3 pancakes every 6 minutes, that is a rate of:

• 3 pancakes per 6 minutes

• 0.5 pancakes per minute

• 30 pancakes per hour

• an hourly rate of 30

By formula the rate of change = Change in cost/ Time taken

=( $980 - $420)/ 8years

= $460/ 8 years

= $57.5 per year

Thus the rate of change of stamp collection was $57.5 per year.

Learn more about rate here :

brainly.com/question/12786410

#SPJ4

4 0

1 year ago

Total donations at the firemans ball failed to reach $940

kumpel [21]

That sucks they should've worked harder

8 0

2 years ago

Find the volume of the cone. Use 3.14 for pi.

Andreyy89

Answer:

V = 628

Step-by-step explanation:

Formula to find volume(V) of cone:

$v = \frac{1}{3} \pi {r}^{2} h$

6 0

2 years ago