All categories

3 years ago

Which expression is equivalent to 647 times 39.

Mathematics

1 answer:

Maru [420]3 years ago

7 0

Answer:

he answer would be A. 1 1/5

Step-by-step explanation:

48/40 = 1 8/40

1 8/40 Simplify to 1 1/5

You might be interested in

Mrs. Potter divides the Grade 8 class of 21 students into few equal groups. The number of

Yuri [45]

Answer:

Step-by-step explanation:

list of prime numbers from 1-21

2,3,5,7,11,13,17,19

he has 21 students

the only numbers he can divide by is 3 and 7

21/3=7

21/7=3

7 0

2 years ago

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

-3 (9x +20) > 15x -20

KengaRu [80]

-27x - 60 > 15x - 20
+27x +20 +27x +20

-40= 42x

-20
----- = x Is this correct?
21

3 0

3 years ago

The amount of soda a dispensing machine pours into a 12-ounce can of soda follows a normal distribution with a mean of 12.30 oun

Ugo [173]

Answer: A) .1587

Step-by-step explanation:

Given : The amount of soda a dispensing machine pours into a 12-ounce can of soda follows a normal distribution with a mean of 12.30 ounces and a standard deviation of 0.20 ounce.

i.e. $\mu=12.30$ and $\sigma=0.20$

Let x denotes the amount of soda in any can.

Every can that has more than 12.50 ounces of soda poured into it must go through a special cleaning process before it can be sold.

Then, the probability that a randomly selected can will need to go through the mentioned process = probability that a randomly selected can has more than 12.50 ounces of soda poured into it =

$P(x>12.50)=1-P(x\leq12.50)\\\\=1-P(\dfrac{x-\mu}{\sigma}\leq\dfrac{12.50-12.30}{0.20})\\\\=1-P(z\leq1)\ \ [\because z=\dfrac{x-\mu}{\sigma}]\\\\=1-0.8413\ \ \ [\text{By z-table}]\\\\=0.1587$

Hence, the required probability= A) 0.1587

6 0

2 years ago

If 8 times a number is added to twice the number, the result is 60. the solution is

Andrei [34K]

Answer:

(8 * x) + 2x = 60

8x + 2x = 60

10x = 60

/10 /10

x = 6

8 is a constant that is being multiplied by an unknown number which we will name x. It is then being added to two times the unknown number(x), so we multiply x by 2, which is 2x. The final product will be 60, so in the equation it'll then equal 60.

We consider "a number" to be a variable that withholds an unknown value, which is x (or any other variable you prefer).

3 0

2 years ago

Read 2 more answers