19,999 round to the nearest thousand

Consider a discrete random variable x with pmf px (1) = c 3 ; px (2) = c 6 ; px (5) = c 3 and 0 otherwise, where c is a positive

PtichkaEL [24]

Looks like the PMF is supposed to be

$\mathbb P(X=x)=\begin{cases}\dfrac c3&\text{for }x\in\{1,5\}\\\\\dfrac c6&\text{for }x=2\\\\0&\text{otherwise}\end{cases}$

which is kinda weird, but it's not entirely clear what you meant...

Anyway, assuming the PMF above, for this to be a valid PMF, we need the probabilities of all events to sum to 1:

$\displaystyle\sum_{x\in\{1,2,5\}}\mathbb P(X=x)=\dfrac c3+\dfrac c6+\dfrac c3=\dfrac{5c}6=1\implies c=\dfrac65$

Next,

$\mathbb P(X>2)=\mathbb P(X=5)=\dfrac c3=\dfrac25$

$\mathbb E(X)=\displaystyle\sum_{x\in\{1,2,5\}}x\,\mathbb P(X=x)=\dfrac c3+\dfrac{2c}6+\dfrac{5c}3=\dfrac{7c}3=\dfrac{14}5$

$\mathbb V(X)=\mathbb E\bigg((X-\mathbb E(X))^2\bigg)=\mathbb E(X^2)-\mathbb E(X)^2$
$\mathbb E(X^2)=\displaystyle\sum_{x\in\{1,2,5\}}x^2\,\mathbb P(X=x)=\dfrac c3+\dfrac{4c}6+\dfrac{25c}3=\dfrac{28c}3=\dfrac{56}5$
$\implies\mathbb V(X)=\dfrac{56}5-\left(\dfrac{14}5\right)^2=\dfrac{84}{25}$

If $Y=X^2+1$ , then $X^2=Y-1\implies X=\sqrt{Y-1}$ , where we take the positive root because we know $X$ can only take on positive values, namely 1, 2, and 5. Correspondingly, we know that $Y$ can take on the values $1^2+1=2$ , $2^2+1=5$ , and $5^2+1=26$ . At these values of $Y$ , we would have the same probability as we did for the respective value of $X$ . That is,

$\mathbb P(Y=y)=\begin{cases}\dfrac c3&\text{for }y=2\\\\\dfrac c6&\text{for }y=5\\\\\dfrac c3&\text{for }y=26\\\\0&\text{otherwise}\end{cases}$

Part (5) is incomplete, so I'll stop here.

8 0

2 years ago

Tonisha has a lemonade stand. She has 31 dollars in expenses and wants to make at least 66 dollars per day. If x represents the

MAVERICK [17]

Answer:

x-31(Greater than or equal to)66 -->x(greater than or equal to)97

Step-by-step explanation:

SHe wants to make a profit of 66, but with 31 bucks in expenses, this would need the revenue to be greater than 97 to cover the expenses and still make the profit

5 0

2 years ago

Which number is greater 17×10^8 4×10^8

Sunny_sXe [5.5K]

Answer:

17×10^8 is greater

Step-by-step explanation:

The expontent comes first which gives you

1000000000 then you multiply that with 17 to get

1700000000

3 0

2 years ago

Read 2 more answers

The number of pieces of popcorn in a large movie theatre popcorn bucket is normally distributed, with a mean of 1610 and a stand

romanna [79]

Answer:

A

Step-by-step explanation:

We know that in normal distribution, approximately 34% of bags will fall with in one standard deviation on one side. On both sides within the range of 1 standard deviation, 34 + 34 = 68 % of bags will fall.

Our range is:

1600 to 1620

1610 - 10 to 1610 + 10

So the answer is 1

That means, that 68% is the answer.

7 0

2 years ago

Read 2 more answers

Sample Response: You would graph the equation f(x) = –x + 3 for input values less than 2. There would be an open circle at the p

fgiga [73]

Answer:

Step-by-step explanation:

What did you include in your response? Check all that apply.

There would be an open circle at (2, 1). Yes

There would be a closed circle at (2, 3). Yes

There would be an open circle at (4, 3). Yes

There would be a closed circle at (4, −4). Yes

Endpoints that are not included in the domain of a particular piece of a function are represented by an open circle. Yes

7 0

1 year ago