Just doing this for fun 50 points. <br><br> 12 * 12

g An urn contains 150 white balls and 50 black balls. Four balls are drawn at random one at a time. Determine the probability th

xxTIMURxx [149]

Answer:

With replacement, 0.2109 = 21.09% probability that there are 2 black balls and 2 white balls in the sample.

Without replacement, 0.2116 = 21.16% probability that there are 2 black balls and 2 white balls in the sample.

Step-by-step explanation:

For sampling with replacement, we use the binomial distribution. Without replacement, we use the hypergeometric distribution.

Binomial probability distribution

The binomial probability is the probability of exactly x successes on n repeated trials, and X can only have two outcomes.

$P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}$

In which $C_{n,x}$ is the number of different combinations of x objects from a set of n elements, given by the following formula.

$C_{n,x} = \frac{n!}{x!(n-x)!}$

And p is the probability of X happening.

Hypergeometric distribution:

The probability of x sucesses is given by the following formula:

$P(X = x) = h(x,N,n,k) = \frac{C_{k,x}*C_{N-k,n-x}}{C_{N,n}}$

In which:

x is the number of sucesses.

N is the size of the population.

n is the size of the sample.

k is the total number of desired outcomes.

$C_{n,x}$ is the number of different combinations of x objects from a set of n elements, given by the following formula.

$C_{n,x} = \frac{n!}{x!(n-x)!}$

Sampling with replacement:

I consider a success choosing a black ball, so $p = \frac{50}{150+50} = \frac{50}{200} = 0.25$

We want 2 black balls and 2 white, 2 + 2 = 4, so $n = 4$ , and we want P(X = 2).

$P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}$

$P(X = 2) = C_{4,2}.(0.25)^{2}.(0.75)^{2} = 0.2109$

With replacement, 0.2109 = 21.09% probability that there are 2 black balls and 2 white balls in the sample.

Sampling without replacement:

150 + 50 = 200 total balls, so $N = 200$

Sample of 4, so $n = 4$

50 are black, so $k = 50$

We want P(X = 2).

$P(X = 2) = h(2,200,4,50) = \frac{C_{50,2}*C_{150,2}}{C_{200,4}} = 0.2116$

Without replacement, 0.2116 = 21.16% probability that there are 2 black balls and 2 white balls in the sample.

3 0

3 years ago

What is 125 divided by 3 ?

Anastasy [175]

41.666666666666..............

4 0

3 years ago

Read 2 more answers

A large cylindrical cooler is 2 (1 )/2 feet high and has a diameter of 1 1/2 feet. It is filled 3/4 high with water for athletes

Ivahew [28]

So.. if hmm check the picture below, the radius is half that diameter

thus $\bf \textit{volume of a cylinder}\\\\
V=\pi r^2 h\qquad 
\begin{cases}
h=height\\
r=radius=\frac{diameter}{2}\\
----------\\
h=2\frac{1}{2}\to \cfrac{5}{2}\\
diameter=1\frac{1}{2}\to \cfrac{3}{2}\\
r=\cfrac{\frac{3}{2}}{2}\to \cfrac{3}{4}
\end{cases}\implies V=\pi \left( \cfrac{3}{4} \right)^2\cfrac{5}{2}
\\\\\\
V=\pi \cdot \cfrac{9}{16}\cdot \cfrac{5}{2}\impliedby \textit{how much is }\frac{3}{4}\textit{ of that?}
\\\\\\
\cfrac{3}{4}\left( \pi \cdot \cfrac{9}{16}\cdot \cfrac{5}{2} \right)$

simplify that away

now.. that's how much is in the cooler in cubic feet though, not in gallons

notice, our units were in feet, thus our volume is also in feet, just cubics

so. to know how many gallons, simply divide that by 231

$\bf \cfrac{\frac{3}{4}\left( \pi \cdot \frac{9}{16}\cdot \frac{5}{2} \right)}{231}\quad gallons$