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2 years ago

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The newest invention of the 6.431x staff is a three-sided die. On any roll of this die, the result is 1 with probability 1/2, 2

with probability 1/4, and 3 with probability 1/4. Consider a sequence of six independent rolls of this die. Find the probability that exactly two of the rolls result in a 3.

1 answer:

Gwar [14]2 years ago

4 0

Answer:

<h2>The answer is 0.23(approx).</h2>

Step-by-step explanation:

The given die is a three sided die, hence, there are only three possibilities of getting the outcomes.

We need to find the probability of getting exactly 3s as the result.

From the sequence of 6 independent rolls, 2 rolls can be chosen in $^6C_2 = \frac{6!}{2!\times4!} = \frac{30}{2} = 15$ ways.

The probability of getting two 3 as outcome is $\frac{1}{4} \times\frac{1}{4} = \frac{1}{16}$ .

In the rest of the 4 sequences, will not be any 3 as outcome.

Probability of not getting a outcome rather than 3 is $1 - \frac{1}{4} = \frac{3}{4}$ .

Hence, the required probability is $15\times\frac{1}{16}(\frac{3}{4})^4 = \frac{1215}{4096}$ ≅0.2966 or, 0.23.

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2 years ago

Sierra is selling bracelets to raise money for the Language Club at school. Each bracelet with yellow beads sells for $5. Each b

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Answer:

Correct answer is:

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Step-by-step explanation:

Given that Number of bracelets with yellow beads is represented by $y$

Each bracelet with yellow beads is sold for $5.

Total money raised by bracelets with yellow beads = Number of bracelets sold $\times$ Money raised by sale of one such bracelet = $5y$

Also Given that Number of bracelets with Orange beads is represented by $r$

Each bracelet with orange beads is sold for $6.

Total money raised by bracelets with orange beads = Number of bracelets sold $\times$ Money raised by sale of one such bracelet = $6r$

Given that total money raised by sale of both type of bracelets is $660.

so, the first equation becomes:

$5y+6r=660 ....... (1)$

It is also given that "<em>The number of bracelets with yellow beads that Sierra sold is 8 more than twice the number of bracelets with orange beads</em>"

$\Rightarrow r =2r+8 ...... (2)$

So, by equation (1) and (2), the system of equations is:

$5y+6r=660\\y=2r+8$

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1 year ago

Hello, I was wondering if someone would be able to help me with this problem I'm on. Thanks :)

koban [17]

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1 year ago

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1 year ago

The U.S. Energy Information Administration (US EIA) reported that the average price for a gallon of regular gasoline is $2.94. T

Anit [1.1K]

Answer:

a) 25

b) 67

c) 97

Step-by-step explanation:

We have that to find our $\alpha$ level, that is the subtraction of 1 by the confidence interval divided by 2. So:

$\alpha = \frac{1-0.95}{2} = 0.025$

Now, we have to find z in the Ztable as such z has a pvalue of $1-\alpha$ .

So it is z with a pvalue of $1-0.025 = 0.975$ , so $z = 1.96$

Now, find the margin of error M as such

$M = z*\frac{\sigma}{\sqrt{n}}$

In which $\sigma$ is the standard deviation of the population and n is the size of the sample. In this problem, $\sigma = 0.25$

(a) The desired margin of error is $0.10.

This is n when M = 0.1. So

$M = z*\frac{\sigma}{\sqrt{n}}$

$0.1 = 1.96*\frac{0.25}{\sqrt{n}}$

$0.1\sqrt{n} = 1.96*0.25$

$\sqrt{n} = \frac{19.6*0.25}{0.1}$

$(\sqrt{n})^{2} = (\frac{19.6*0.25}{0.1})^{2}$

$n = 24.01$

Rounding up to the nearest whole number, 25.

(b) The desired margin of error is $0.06.

This is n when M = 0.06. So

$M = z*\frac{\sigma}{\sqrt{n}}$

$0.06 = 1.96*\frac{0.25}{\sqrt{n}}$

$0.06\sqrt{n} = 1.96*0.25$

$\sqrt{n} = \frac{19.6*0.25}{0.06}$

$(\sqrt{n})^{2} = (\frac{19.6*0.25}{0.06})^{2}$

$n = 66.7$

Rounding up, 67

(c) The desired margin of error is $0.05.

This is n when M = 0.05. So

$M = z*\frac{\sigma}{\sqrt{n}}$

$0.05 = 1.96*\frac{0.25}{\sqrt{n}}$

$0.05\sqrt{n} = 1.96*0.25$

$\sqrt{n} = \frac{19.6*0.25}{0.05}$

$(\sqrt{n})^{2} = (\frac{19.6*0.25}{0.05})^{2}$

$n = 96.04$

Rounding up, 97

8 0

1 year ago