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2 years ago

I've been stuck on this question for 3 days ;< halp meh ples

Mathematics

1 answer:

zimovet [89]2 years ago

4 0

Answer:

avg time = total time/ 3

for big car :-

= 4.46/ 3

= 1.48

for small car :-

= 5.14/ 3

= 1.71

avg speed = total distance/ total time

for big car:-

= 2/ 4.46

= 0.45

for small car :-

= 2/ 5.14

= 0.4

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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

3 years ago

jacob has a box of 2 hundred cubes he also has a bag of 40 cubes. how many trains of 10 cubes can hw make?

Verizon [17]

200+40=240
each train cost 10
take 240/10=24trains

6 0

3 years ago

Help me pleasee pleaseee

Minchanka [31]

Answer:

WHAT IS YOUR QUESTION

Step-by-step explanation:

5 0

1 year ago

Read 2 more answers

Solve |y + 2| > 6 i dont understand this, please help

Lisa [10]

y < - 8 or y > 4

inequalities of the form | x | > a always have solutions of the form

x < - a or x > a

we have to solve

y + 2 < - 6 or y + 2 > 6

y + 2 < - 6 ( subtract 2 from both sides )

y < - 8

y + 2 > 6 ( subtract 2 from both sides )

y > 4

these can be combined using interval notation

y ∈ (- ∞, - 8 ) ∪ (4, ∞ )

As a check

substitute chosen values of x from each interval

y = - 10 : | - 10 + 2 | = | - 8 | = 8 > 6 this is true

y = 12 : | 12 + 2 | = | 14 | = 14 > 6 which is also true

7 0

2 years ago

1. a) Solve the following quadratic-quadratic system of equations graphically.

anastassius [24]

Answer:

see explanation

Step-by-step explanation:

look at the photo

4 0

1 year ago