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3 years ago

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If the radius of the Earth is roughly 3,960 miles, how many times larger is the volume of the Earth than the volume of a ping-po

ng ball? A ping-pong ball has a radius of 0.7441 inches. 1 mile = 5,280 feet.

1 answer:

qaws [65]3 years ago

8 0

The volume of the Earth is 2.21865*10²² times larger than the volume of a ping-pong ball

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If (m, −3) is on a circle with center (2, −3) and radius 7, what is a value of m?

kvv77 [185]

Ok so
distance from (m,-3) to (2,-3) is 7 units

since the y value is the same, we don't even need to use distance formula

see how far 7 units from 2 is
-5 or 9
m can be -5 or 9
the point can be (-5,-3) or (9,-3)

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3 years ago

Choose scales for the coordinate plane shown so that you can graph points J(2,40), K(3,10), L(3,-40),M(-4,50) and N(-5,-50). exp

Afina-wow [57]

Answer:

The scale of y-axis is 10, and the scale of x-axis is 1.

Step-by-step explanation:

The y-coordinates of points J, K,L,M, and N are divisible by 10, so it would be convenient to scale the y-axis to 10, doing so will result in a graph that does not occupy too much space and is therefore easier to read.

The x-coordinates of points J, K,L,M, and N are integers less than 10. Our graph will be easier to read if we scale the x-axis to 1, because then we get a graph whose x-coordinate is marked such that the x values of the points can be easily related.

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3 years ago

A silk worm grows twice asd long as it was the day before .If the worm measures v40 mm on the 10 th day, on which day was it 2.5

Arte-miy333 [17]

Answer:

On the sixth day (10 - 4), the worm was 2.5mm long.

Step-by-step explanation:

Giving the following information:

Future Value= 40mm

Present Value= 2.5mm

Number of periods (n)= ?

Growth rate= 100% per day

<u>First, we need to calculate the number of days it will take to grow from 2.5mm (PV) to 40mm (FV):</u>

<u></u>

n= ln(FV/PV) / ln(1+i)

n= ln (40 / 2.5) / ln (2)

n= 4

It will take 4 days.

On the sixth day (10 - 4), the worm was 2.5mm long.

3 0

3 years ago

5.2.14. For the negative binomial pdf p (k; p, r) = k+r−1 (1 − p)kpr, find the maximum likelihood k estimator for p if r is know

Volgvan

Answer:

$\hat p = \frac{r}{\bar x +r}$

Step-by-step explanation:

A negative binomial random variable "is the number X of repeated trials to produce r successes in a negative binomial experiment. The probability distribution of a negative binomial random variable is called a negative binomial distribution, this distribution is known as the Pascal distribution".

And the probability mass function is given by:

$P(X=x) = (x+r-1 C k)p^r (1-p)^{x}$

Where r represent the number successes after the k failures and p is the probability of a success on any given trial.

Solution to the problem

For this case the likehoof function is given by:

$L(\theta , x_i) = \prod_{i=1}^n f(\theta ,x_i)$

If we replace the mass function we got:

$L(p, x_i) = \prod_{i=1}^n (x_i +r-1 C k) p^r (1-p)^{x_i}$

When we take the derivate of the likehood function we got:

$l(p,x_i) = \sum_{i=1}^n [log (x_i +r-1 C k) + r log(p) + x_i log(1-p)]$

And in order to estimate the likehood estimator for p we need to take the derivate from the last expression and we got:

$\frac{dl(p,x_i)}{dp} = \sum_{i=1}^n \frac{r}{p} -\frac{x_i}{1-p}$

And we can separete the sum and we got:

$\frac{dl(p,x_i)}{dp} = \sum_{i=1}^n \frac{r}{p} -\sum_{i=1}^n \frac{x_i}{1-p}$

Now we need to find the critical point setting equal to zero this derivate and we got:

$\frac{dl(p,x_i)}{dp} = \sum_{i=1}^n \frac{r}{p} -\sum_{i=1}^n \frac{x_i}{1-p}=0$

$\sum_{i=1}^n \frac{r}{p} =\sum_{i=1}^n \frac{x_i}{1-p}$

For the left and right part of the expression we just have this using the properties for a sum and taking in count that p is a fixed value:

$\frac{nr}{p}= \frac{\sum_{i=1}^n x_i}{1-p}$

Now we need to solve the value of $\hat p$ from the last equation like this:

$nr(1-p) = p \sum_{i=1}^n x_i$

$nr -nrp =p \sum_{i=1}^n x_i$

$p \sum_{i=1}^n x_i +nrp = nr$

$p[\sum_{i=1}^n x_i +nr]= nr$

And if we solve for $\hat p$ we got:

$\hat p = \frac{nr}{\sum_{i=1}^n x_i +nr}$

And if we divide numerator and denominator by n we got:

$\hat p = \frac{r}{\bar x +r}$

Since $\bar x = \frac{\sum_{i=1}^n x_i}{n}$

4 0

3 years ago

A set of mathematics exam scores are normally distributed with a mean of 80.280.280, point, 2 points and a standard deviation of

Ugo [173]

Answer:

0.2379

lmk if im wrong :)

5 0

2 years ago