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3 years ago

Its a TEST pls help !!!! i beg

Mathematics

1 answer:

ad-work [718]3 years ago

3 0

Answer:

Step-by-step explanation:

-8 + 5 = -3

10 + - 4 = 6

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A phycologist is interested in determining the proportion of algae samples from a local rivulet that belong to a particular phyl

LuckyWell [14K]

Answer:

A sample of 16577 is required.

Step-by-step explanation:

In a sample with a number n of people surveyed with a probability of a success of $\pi$ , and a confidence level of $1-\alpha$ , we have the following confidence interval of proportions.

$\pi \pm z\sqrt{\frac{\pi(1-\pi)}{n}}$

In which

z is the z-score that has a p-value of $1 - \frac{\alpha}{2}$ .

The margin of error is of:

$M = z\sqrt{\frac{\pi(1-\pi)}{n}}$

99% confidence level

So $\alpha = 0.01$ , z is the value of Z that has a p-value of $1 - \frac{0.01}{2} = 0.995$ , so $Z = 2.575$ .

She wants to estimate the proportion using a 99% confidence interval with a margin of error of at most 0.01. How large a sample size would be required?

We have no estimation for the proportion, and thus we use $\pi = 0.5$ , which is when the largest sample size will be needed.

The sample size is n for which M = 0.01. So

$M = z\sqrt{\frac{\pi(1-\pi)}{n}}$

$0.01 = 2.575\sqrt{\frac{0.5*0.5}{n}}$

$0.01\sqrt{n} = 2.575*0.5$

$\sqrt{n} = \frac{2.575*0.5}{0.01}$

$(\sqrt{n})^2 = (\frac{2.575*0.5}{0.01})^2$

$n = 16576.6$

Rounding up:

A sample of 16577 is required.

8 0

3 years ago

The approximate distance between J and K is units. The approximate distance between K and L is units. The approximate distance b

Dima020 [189]

Count the distance d, which gives you 7.

Use Pythogarean theorem to find c:
${a}^{2} + {b}^{2} = {c}^{2}$
Plug in the numbers:
${4}^{2} + {3}^{2} = {c}^{2} \\ \\ = 16 + 9 \\ \\ = 25 \\ \\ c = \sqrt{25} = 5$
c is 5.

Same thing with g:
${e}^{2} + {f}^{2} = {g}^{2} \\ \\ {g}^{2} = {4}^{2} + {4}^{2} \\ \\ = 16 + 16 \\ \\ = 32 \\ \\ g = \sqrt{32} = 4 \sqrt{2} = 5.66$
g equals 5.66.

7 0

4 years ago

Family Video charges $10 for

Irina18 [472]

Answer:

4 movies, $20

Step-by-step explanation:

Given data

Family Video

charges $10 for a monthly membership and

$2.50 per movie

let the number of movies be x

and the charge for x movies be y

y= 10+2.5x----------1

Babe's Movies

charges a $12

membership and $2 per

movie.

let the number of movies be x

and the charge for x movies be y

y= 12+2x----------2

equate 1 and 2

10+2.5x= 12+2x

collect like terms

12-10= 2.5x-2x

2= 0.5x

x= 2/0.5

x= 4 movies

put x= 4 in equation 1 or 2

y= 12+2x----------2

y= 12+2*4

y= 12+8

y= $20

4 0

3 years ago

2.) You need a carpet installed in your living room. You reach out to 2 different companies

Oliga [24]

Answer:

Home Depot

Step-by-step explanation:

Home Depot Has better charges because you have to multiply the question to see which one is lower.

7 0

4 years ago

A bag contains 8 black beads and 4 white beads. If 2 beads are drawn at random, what is the probability that both beads are blac

maria [59]

Answer:

14/33

Step-by-step explanation:

The total amount of beads is 8+4 = 12. 8 of these are black beads, so that is what we want, so 8/12 or 2/3. For the second one, one black bead is already taken so 8-1 = 7 are left and for the total 12 - 1 = 11 are left, so 7/11. Multiply this by 2/3 and we get 14/33.

3 0

3 years ago