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3 years ago

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1. Below is data collected from a random sample of 40 people at the public library. If the public library has 300 people, then w

hat is a reasonable estimate for the number of people who enjoy reading mysteries?
NON- FICTION 19 people
MYSTERY 12 people
SCIENCE FICTION 9 people

1 answer:

nataly862011 [7]3 years ago

5 0

Answer:

please do the math luke a lesson and the beta is very weird so you want to do something about that so i suggest that you do 300.

You might be interested in

Suppose the method of tree ring dating gave the following dates A.D. for an archaeological excavation site. Please show your wor

natita [175]

Answer:

a) $\bar X=\frac{1245+1245+1321+1191+1295+1330+1239+1250+1228}{9}= 1260.444$

b) $s =\sqrt{\frac{\sum_{i=1}^n (X_i -\bar X)^2}{n-1}}$

And if we replace we got:

$s = 45.580$

c) For this case since the sampel size is n=9 <30 we can use the t distribution in order to find the confidence interval.

d) $1260.444-2.306 \frac{45.580}{\sqrt{9}}= 1225.408$

$1260.444+2.306 \frac{45.580}{\sqrt{9}}= 1295.480$

Step-by-step explanation:

For this case we ave the following data:

1245 1245 1321 1191 1295 1330 1239 1250 1228

Part a

We can calculate the sample mean with the following formula:

$\bar X = \frac{\sum_{i=1}^n X_i}{n}$

And if we replace we got:

$\bar X= \frac{1245+1245+1321+1191+1295+1330+1239+1250+1228}{9}= 1260.444$

Part b

For this case we can use the following formula in order to find the sample standard deviation:

$s =\sqrt{\frac{\sum_{i=1}^n (X_i -\bar X)^2}{n-1}}$

And if we replace we got:

$s = 45.580$

Part c

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".

The margin of error is the range of values below and above the sample statistic in a confidence interval.

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

For this case since the sampel size is n=9 <30 we can use the t distribution in order to find the confidence interval.

Part d

The confidence interval for the mean is given by the following formula:

$\bar X \pm t_{\alpha/2}\frac{s}{\sqrt{n}}$ (1)

We need to find the degrees of freedom given by:

$df = n-1 = 9-1=8$

Since the Confidence is 0.95 or 95%, the value of $\alpha=1-0.95=0.05$ and $\alpha/2 =0.025$ , and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-T.INV(0.025,8)".And we see that $t_{\alpha/2}=2.306$

Now we have everything in order to replace into formula (1):

$1260.444-2.306 \frac{45.580}{\sqrt{9}}= 1225.408$

$1260.444+2.306 \frac{45.580}{\sqrt{9}}= 1295.480$

8 0

4 years ago

The dimensions of a rectangle are such that its length is 3 in. more than its width. If the length were doubled and if the width

Kay [80]

Answer:

The length of the rectangle is 11 inch and its width is 8 inch.

Step-by-step explanation:

Given:

Rectangle $(R_1)$ and rectangle $(R_2)$ .

Let the width of the rectangle be 'x' inch.

Its length = '(x+3)' inch

Area of the rectangle = $(A_1)$

⇒ $A_1$ = $(x)(x+3)$

Now for rectangle $(R_2)$ its width is decreased by 1 inch and length is doubled,the area $(A_2)$ will increased by 66 sq-inch.

So,

$A_2=A_1+66$

According to the question.

⇒ Area of rectangle $(R_2)$ with width '(x-1)' and length '2(x+3)'='(2x+6)' .

⇒ $A_2=(x-1)(2x+6)$

Plugging the values of $A_2$ in terms of $A_1$ .

⇒ $A_1+66= (x-1)(2x+6)$

Plugging $A_1$ = $(x)(x+3)$ into the equation.

⇒ $(x)(x+3)+66=(x-1)(2x+6)$

⇒ $x^2+3x+66=2x^2+6x-2x-6$

⇒ $x^2-2x^2+3x-6x+2x+6+66=0$

⇒ $-x^2-x+72=0$

Now using quadratic formula we can find the value of 'x'.

Quadratic formula, (x)= $\frac{\pm b+\sqrt{b^2-4ac} }{2a}$

x= -9 and x= 8

Discarding the negative value.

Our width = 'x' = 8 inches.

So the length of the rectangle = 11 inches and width of the rectangle = 8 inches.

7 0

3 years ago

A°<br> D<br> B<br> 120°<br> Angle A =<br> degrees.

Paha777 [63]

Answer:

60

Step-by-step explanation:

You dont have enough infor, but if its 120 degrees, A total degree of a triangle is 180, so 180-120 equals 60

4 0

3 years ago

Question number 41 only . thank you

docker41 [41]

Answer:

x^2 +y^2

Step-by-step explanation:

Dude this is Pythragorean Theorem =)).

You may have missed this part of your lesson. It's ok and also not ok at the same time beacause pythagorean theorem is a meme.

Ok I'll explain once =)).

Thousands of years ago, a mathematician named Pythagore found out that if we have 3 squares, with one square's area equals to the sum of two other squares, then when we put the sides of the squares together to form a triangle , it'll always be a right triangle ( a triangle with one of its angle is 90°). A square area is measured by the length of its side multipled by itself. So he came up with the statement : In a right triangle, the length of the hypotenuse( the side that does not connect to the right angle) is equalled to the sum of squared other sides.

EG.

In this triangle, the right angle is ^ACB. If length of BC is <em>a</em><em>,</em><em> </em>length of AB is <em>c</em>, length of BC is <em>a</em>

A

I We have a formula :

I \ <em>a</em>^2 + <em>b</em>^2 = <em>c</em>^2

I \

I \

I <em>b</em> \ <em>c</em>

I \

I \

I______\

C <em> a </em> B

So now you can use pythagorean theorem to show off =)).

HOPE YOU LEARN WITH JOY AND HIGH GRADES !!!

7 0

3 years ago

I need help u suck at word problems

lutik1710 [3]

I would solve this by calculating the percentage of dislikes that makes up to this amount of likes:

First one, "The True Science of Parallel Universes" would be:

5/300)*100 = 1.66

Second one, "did the Past Really Happen?" would be:

7/400)*100 = 1.75

The first one has less dislikes compared to likes. So "The True Science of Parallel Universes" is the video that is better liked

8 0

2 years ago