Identify whether the sampling method is simple random, systematic, stratified, cluster, or convenience. Explain.

In a nationwide study of registered voters conducted by The New York Times, 390 people are randomly selected out of those registered as Republicans, 430 people are randomly selected out of those registered as Democrats, and 180 people are randomly selected out of those registered as Independents.

Answers

Answer 1

Answer: stratified

Step-by-step explanation:

In stratified sampling, you divide the population into subgroups, or strata, with similar characteristics, like here we have divided the population into subgroups that depend on their political alignment. This is used when you can expect that the results have a noticeable variation between the different subgroups. Usually, you want to have the same number of population for eac subgroup, but sometimes it is hard for different reasons (not enough people in one subgroup, for example)

In cluster sampling we also use subgroups, but the subgroup itself is the unit of the sampling, while in this case, we are randomly selecting individuals of the given subgroups.

So this would be a "stratified sampling".


Related Questions

The odds in favor of a horse winning a race are 7:4. Find the probability that the horse will win the race.

Answers

Answer:

7/11 = 0.6363...

Step-by-step explanation:

7 + 4 = 11

probability of winning: 7/11 = 0.6363...

The probability that the horse will in the race is [tex]\mathbf{\dfrac{7}{11}}[/tex]

Given that the odds  of the horse winning the race is 7:4

Assuming the ratio is in form of a:b, the probability of winning the race can be computed as:

[tex]\mathbf{P(A) = \dfrac{a}{a+b}}[/tex]

From the given question;

The probability of the horse winning the race is:

[tex]\mathbf{P(A) = \dfrac{7}{7+4}}[/tex]

[tex]\mathbf{P(A) = \dfrac{7}{11}}[/tex]

Learn more about probability here:

https://brainly.com/question/11234923?referrer=searchResults

find m<SPT in degrees​

Answers

Answer:  60°

Step-by-step explanation:

∠UQR = 180°

∠UQR = ∠UQ + ∠QR

  180° =  115° + ∠QR

   65° = ∠QR

∠QRT = 180°

∠QRT = ∠QR + ∠RS + ∠ST

  180° =  65° + ∠RS  +  55°

  180° = 120° + ∠RS

   60° = ∠RS

Given the following hypotheses: H0: μ = 490 H1: μ ≠ 490 A random sample of 15 observations is selected from a normal population. The sample mean was 495 and the sample standard deviation 9. Using the 0.01 significance level:
a.) State the decision rule.
b.) Compute the value of the test statistic.
c.) What is your decision regarding the null hypothesis?

Answers

Answer:

We conclude that the population mean is equal to 490.

Step-by-step explanation:

We are given that a random sample of 15 observations is selected from a normal population. The sample mean was 495 and the sample standard deviation 9.

Let [tex]\mu[/tex] = population mean.

So, Null Hypothesis, [tex]H_0[/tex] : [tex]\mu[/tex] = 490      {means that the population mean is equal to 490}

Alternate Hypothesis, [tex]H_A[/tex] : [tex]\mu\neq[/tex] 490     {means that the population mean is different from 490}

The test statistics that will be used here is One-sample t-test statistics because we don't know about population standard deviation;

                               T.S.  =  [tex]\frac{\bar X-\mu}{\frac{s}{\sqrt{n} } }[/tex]  ~ [tex]t_1_4[/tex]

where, [tex]\bar X[/tex] = sample mean = 495

            s = sample standard deviation = 9

             n = sample of observations = 15

So, the test statistics =   [tex]\frac{495-490}{\frac{9}{\sqrt{15} } }[/tex]  ~ [tex]t_1_4[/tex]

                                     =  2.152

The value of t-test statistics is 2.152.

Now, at a 0.01 level of significance, the t table gives a critical value of -2.977 and 2.977 at 14 degrees of freedom for the two-tailed test.

Since the value of our test statistics lies within the range of critical values of t, so we have insufficient evidence to reject our null hypothesis as the test statistics will not fall in the rejection region.

Therefore, we conclude that the population mean is equal to 490.

A type of related samples design in which participants are observed more than once is called a
A. repeated measures design
B. matched pairs design
C. matched samples design
D. both matched pairs design and matched samples design

Answers

Answer:

Option A (repeated measures design) is the correct option.

Step-by-step explanation:

Researchers as well as statisticians vary in terms of methods used mostly for repetitive measurements. Besides illustration, repeated models of measurements are however recognized as repeated analyzes of variance measurements, standardized considerations of measurements, or layouts of objects throughout them.

The other three options are not related to the given instance. So that alternative A would be the correct choice.

Find the indicated complement. A certain group of women has a 0.12​% rate of​ red/green color blindness. If a woman is randomly​ selected, what is the probability that she does not have​ red/green color​ blindness?

Answers

Answer:

the probability will be 0.

Step-by-step explanation:

0.12%= 0.0012= 3/2500.

A group of fitness club members lose a combined total of 28 kilograms in 1 week. There are approximately 2.2 pounds in 1 kilogram. Assuming the weight loss happened at a constant rate, about how many pounds did the group lose each day?

Answers

Answer:

8.8 pounds

Step-by-step explanation:

Given the following :

Combined weight loss which occurred within a week = 28 kg

Number of days in a week = 7 days

1 kilogram (kg) = 2.2 pounds

Combined weight loss in pounds that occurs within a week:

Weight loss in kg × 2.2

28kg * 2.2 = 61.6 pounds

Assume weight loss occurred at a constant rate :

Weight lost by the group per day :

(Total weight loss / number of days in a week)

(61.6 pounds / 7)

= 8.8 pounds daily

Answer:

88

Step-by-step explanation:

Found the answer and I am doing the quiz rn lel

how can i solve this factorial? A 6,2- P6- A 5,3 + P5

Answers

I’m very confused! Is this a math problem!?

Question 2: Jamie has a jar of coins containing the same number of nickels, dimes and quarters. The total value of the coins in the jar is 13.20. How many nickels does Jamie have?

Answers

Answer:

?

Step-by-step explanation:

Answer:

33

Step-by-step explanation:

Let "x" be the number of nickels, of dimes, and of quarters.

The value of the nickels is 5x cents.

The value of the dimes is 10x cents

The value of the quarters is 25x cents.

Equation:

Value of nickels + Value of dimes + Value of quarters =1320 cents

5x + 10x + 25x = 1320

Sove for "x". Then you will know the number of each coin.

Compute the least-squares regression line for the given data set. Use a TI-84 calculator. Round final answers to four decimal places, as needed.
x 5 7 6 2 1
y 4 3 2 5 1
Regression line equation: ŷ = _______ + _______ x.

Answers

Answer:

   Y = 2.843+ 0.037 X

Step-by-step explanation:

Let the equation of the straight line to be fitted to the data , be Y = a+b X where a and b are to be evaluated. The normal equations fro determining a and b are

∑Y = na +b ∑X

∑XY = a∑X + b∑X²

We now calculate ∑X, ∑Y , ∑X², and ∑XY

X                Y                XY              X²

5                  4                 20            25

7                  3              21                49

6                  2                 12            36

2                  5                 10             4

1                    1                1                 1          

21                 15                 64           115  

Thus the normal equation becomes

                                                 5a + 21b =15

                                                21a +115b = 64

Solving these two equations simultaneously we get

                                                105 a + 441b = 315

                                                105a + 575b = 320

                                                            134b= 5

b= 0.037 , a= 2.843

Hence the equation for the required straight line is

                    Y = 2.843+ 0.037 X

A passenger train traveled 180 miles in the same amount of time it took a freight train to travel 120 miles. The rate of the freight train was 15 miles per hour slower than the rate of the passenger train. Find the rate of the passenger train.

Answers

Answer:

The passenger train is moving at 45 miles per hour

Step-by-step explanation:

Let the amount of time it took the two trains to travel the distance = t.

Since the two trains traveled the distance at the same time,

Rate of the passenger train =[tex]\frac{180}{t}[/tex]

Rate of the freight train = [tex]\frac{120}{t}[/tex]

Where t is in hours.

From the problem, we can see that the rate of the freight train was 15 miles per hour slower than the rate of the passenger train. Mathematically, we can represent this as

[tex]\frac{120}{t}= \frac{180}{t}-15[/tex]

from the above equation, we can now get our value for t  as

[tex]\frac{120-180}{t}=-15\\\frac{-60}{t}=-15\\t=4 hours[/tex]

We have our time of travel for the two trains as 4 hours.

The rate of the passenger train can now be calculated by 180/4 = 45 miles per hour

A new fast-food firm predicts that the number of franchises for its products will grow at the rate dn dt = 6 t + 1 where t is the number of years, 0 ≤ t ≤ 15.

Answers

Answer:

The answer is "253"

Step-by-step explanation:

In the given- equation there is mistype error so, the correct equation and its solution can be defined as follows:

Given:

[tex]\bold{\frac{dn}{dt} = 6\sqrt{t+1}}\\[/tex]

[tex]\to dn= 6\sqrt{t+1} \ \ dt.....(a)\\\\[/tex]

integrate the above value:

[tex]\to \int dn= \int 6\sqrt{t+1} \ \ dt \\\\\to n= \frac{(6\sqrt{t+1} )^{\frac{3}{2}}}{\frac{3}{2}}+c\\\\\to n= \frac{(12\sqrt{t+1} )^{\frac{3}{2}}}{3}+c\\\\[/tex]

When the value of n=1 then t=0

[tex]\to 1= \frac{12(0+1)^{\frac{3}{2}}}{3}+c\\\\ \to 1= \frac{12(1)^{\frac{3}{2}}}{3}+c\\\\\to 1-\frac{12}{3}=c\\\\\to \frac{3-12}{3}=c\\\\\to \frac{-9}{3}=c\\\\\to c=-3\\[/tex]

so the value of  n is:

[tex]\to n= \frac{(12\sqrt{t+1} )^{\frac{3}{2}}}{3}-3\\\\[/tex]

when we put the value t= 15 then,

[tex]\to n= \frac{(12\sqrt{15+1} )^{\frac{3}{2}}}{3}-3\\\\\to n= \frac{(12\sqrt{16} )^{\frac{3}{2}}}{3}-3\\\\\to n= \frac{(12\times 64)}{3}-3\\\\\to n= (4\times 64)-3\\\\\to n= 256-3\\\\\to n= 253[/tex]

3
BO
Evaluate the function f(x) = x2 + 4x + 1 at the given values of the independent variable and simplify.
a. f(6)
b. f(x +9)
c. f(-x)

Answers

Answer:

a) f(6)=(6)^2+4(6)+1=65

b)f (x+9)=(x+9)^2+4 (x+9)+1=(x^2+18x+81)+(4x+36)+1=x^2+22x+117

f (-x)=(-x)^2-4x+1

Century Roofing is thinking of opening a new warehouse, and the key data are shown below. The company owns the building that would be used, and it could sell it for $100,000 after taxes if it decides not to open the new warehouse. The equipment for the project would be depreciated by the straight-line method over the project's 3-year life, after which it would be worth nothing and thus it would have a zero salvage value. No new working capital would be required, and revenues and other operating costs would be constant over the project's 3-year life. What is the project's NPV? (Hint: Cash flows are constant in Years 1-3.)

Answers

Question Completion:

WACC = 10.0%

Opportunity cost = $100,000

Net equipment cost (depreciable basis) = $65,000

Straight-line deprec. rate for equipment = 33.333%  

Sales revenues, each year = $123,000

Operating costs (excl. deprec.), each year = $25,000

Tax rate = 35%

Answer:

Century Roofing

Project's NPV is: ($6,578)

Step-by-step explanation:

a) Data and Calculations:

WACC = 10.0%

Opportunity cost = $100,000

Net equipment cost (depreciable basis) = $65,000

Straight-line deprec. rate for equipment = 33.333%  

Sales revenues, each year = $123,000

Operating costs (excl. deprec.), each year = $25,000

Tax rate = 35%

Cash outflow in year 0 = $165,000 (Opportunity and new equipment costs)

Annual Cash inflow = $123,000 - $25,000 - $34,300 = $63,700

PV of annuity for 3 years at 10% = $158,422 ($63,700 x 2.487)

NPV = Cash inflow minus Cash outflow

= $158,422 - $165,000

= ($6,578)

Negative NPV

b) Since Century Roofing could have realized $100,000 from the sale of the building if it decides not to open the new warehouse, this opportunity cost is factored into the calculation of the Net Present Value.  It becomes a present cash outflow.  Century Roofing's opportunity cost is defined as the loss of $100,000 being the future return from the best alternative project when it chooses to build the new warehouse instead of selling off the building.

in the diagram, find the values of a and b.​

Answers

Answer:

           m∠a = 67° ,   m∠b = 42°

Step-by-step explanation:

∠a is alternate interior angle to ∠ECD

∠b is alternate interior angle to ∠BCD

so:

If AB || CD then:

m∠a = m∠ECD = 25° + 42° = 67°

m∠b = 42°

coefficient of 8x+7y

Answers

Answer: I’m pretty sure it is 8 and 7 because those are the numbers multiplied with variables.

Answer:

8

Step-by-step explanation:

Identify the exponents on the variables in each term, and add them together to find the degree of each term.

8x→1

7y→1

The largest exponent is the degree of the polynomial.

1

The leading term in a polynomial is the term with the highest degree.

8x

The leading coefficient of a polynomial is the coefficient of the leading term.

____________________________________________________________

The leading term in a polynomial is the term with the highest degree.

8x

The leading coefficient in a polynomial is the coefficient of the leading term.

8

List the results.

Polynomial Degree: 1

Leading Term: 8x

Leading Coefficient: 8

Hope This Helps!!!

algebra pyramid please answer !! be the first to be marked as a brainliest .

Answers

Answer:

The first pyramid:

      63x

  39x  24x  

23x  16x  8x

The second pyramid:

     162x

 82x  80x  

4x  78x  2x

The third pyramid:

     12a+2b

9a+b   3a+b  

9a     b     3a

The fourth pyramid:

      -19a

  -5a   -14a  

3a   -8a  -6a

   

Step-by-step explanation:

All that an alegbra pyramid is is adding the two terms below it.

So you can see how I added the terms that lied below each number, such as in number 1:  I added 23x and 16x to get me 39x, and I added 16x and 8x to get me 24.

Hope this helped!

13,226 divided by 29

Answers

13226/29= 456.068965517

Which expression is equal to (1+6i)−(7+3i) ?

Answers

Answer:

- 6+3i

Step-by-step explanation:

[tex](1+6i)-(7+3i) ?\\Group\:the\:real\:part\:and\:the\:imaginary\\\:part\:of\:the\:complex\:number\\\left(a+bi\right)\pm \left(c+di\right)=\left(a\:\pm \:c\right)+\left(b\:\pm \:d\right)i\\=\left(1-7\right)+\left(6-3\right)i\\1-7=-6\\6-3=3\\=-6+3i[/tex]

A planet rotates on an axis through its poles and 1 revolution takes 1 day 1 day is 24 hours. The distance from the axis to a location the planet 30 degrees north latitude is about 3387.5 miles.​ Therefore, a location on the planet at 30 degrees north latitude is spinning on a circle of radius 3387.5 miles.

Compute the linear speed on the surface of the planet at 30 degrees north latitude.

Answers

Answer:

The velocity is  [tex]v = 886.96 \ m/s[/tex]

Step-by-step explanation:

From the question we are told that

    The period of each revolution is  [tex]T = 1\ day = 24 \ hours[/tex]

    The angle  is [tex]\theta = 30^o[/tex]

     The radius is  [tex]r = 3387.5 \ miles[/tex]

Generally the linear speed is  mathematically represented as

        [tex]v = w * r[/tex]

Where  [tex]w[/tex] is the angular speed which is mathematically represented as

       [tex]w = \frac{2 \pi }{T}[/tex]

substituting values

       [tex]w = \frac{2 *3.142 }{24}[/tex]

        [tex]w = 0.2618 \ rad/s[/tex]

Thus  

         [tex]v = 0.261833 * 3387.5[/tex]

        [tex]v = 886.96 \ m/s[/tex]

     

Need Assitance
*Show Work*​

Answers

Answer:

66 2/3 %

Step-by-step explanation:

First find the students not in the 8th grade

24 - 8 = 16

16 students are not in the 8th grade

Take the fraction of the students not in the 8th grade over the total

16/24 = 2/3

Change to a decimal

.66666666666

Multiply by 100 to change to a percent

66.666666%

66 2/3 %

Answer:

66.67% of students are not in eighth grade

Step-by-step explanation:

8/24=1/3

1/3=0.33333333333

1-0.33333333333=0.66666666667

0.66666666667=66.67%


Paula drives 130 miles in 2.5 hours. How far would she drive in 4.5 at the same speed?
*Please answer
I will award the Brainliest answer

Answers

Answer:

Paula will travel 234 miles in 4.5 hours

Step-by-step explanation:

Step 1: We first find the speed Paula is going in hours, we divide 130 mile by 2.5 hours to get 52 miles per hour

Step 2: We multiple 52 miles per hour with 4.5 hours to get 234 miles

Therefore Paula will travel 234 miles in 4.5 hours

isted below are amounts​ (in millions of​ dollars) collected from parking meters by a security service company and other companies during similar time periods. Do the limited data listed here show evidence of stealing by the security service​ company's employees? Security Service Company: 1.5 1.7 1.6 1.4 1.7 1.5 1.8 1.4 1.4 1.5 Other Companies: 1.8 1.9 1.6 1.7 1.8 1.9 1.6 1.5 1.7 1.8 Find the coefficient of variation for each of the two​ samples, then compare the variation. The coefficient of variation for the amount collected by the security service company is nothing​%. ​(Round to one decimal place as​ needed.)

Answers

Answer:

Means:

1.55

1.73

Standard Deviation:

0.1434

0.1338

Coefficient of variation:

9.2

7.7

the limited data listed here shows evidence of stealing by the security service​ company's employees.

Step-by-step explanation:

Given data:

security Service Company          Other Companies    

               x                                                 x

               1.5                                              1.8

               1.7                                               1.9

               1.6                                               1.6

               1.4                                                1.7

               1.7                                                 1.8

               1.5                                                 1.9

               1.8                                                 1.6

               1.4                                                  1.5

               1.4                                                  1.7

               1.5                                                  1.8

      n₁ = 10                                                 n₂ = 10

To find:

coefficient of variation for each of the two​ samples

Solution:

The formula for calculating coefficient of variation of sample is:

Coefficient of Variation (CV) = (Standard Deviation / Mean) * 100%

Calculate Mean for Security Service Company data:

Mean =  (Σ x₁) / n₁

         = (1.5 + 1.7 + 1.6 + 1.4 + 1.7 + 1.5 + 1.8 + 1.4 + 1.4 + 1.5) / 10

         = 15.5 / 10

Mean = 1.55

Calculate Standard Deviation for Security Service Company data:

Standard Deviation = √∑(x₁ - Mean)²/n₁-1

                                = √∑(1.5-1.55)² + (1.7-1.55)² + (1.6-1.55)² + (1.4-1.55)² + (1.7-1.55)² + (1.5-1.55)² + (1.8-1.55)² + (1.4-1.55)² + (1.4-1.55)² + (1.5-1.55)² / 10-1

=√∑ (−0.05)² + (0.15)² + (0.05)² + (−0.15)² + (0.15)² + (−0.05)² + (0.25)² +  (−0.15)² +  (−0.15)² +  (−0.05)² / 10 - 1

= √∑0.0025 + 0.0225 + 0.0025 + 0.0225 + 0.0225 + 0.0025 + 0.0625 +        0.0225 + 0.0225 + 0.0025 / 9

= √0.185 / 9

= √0.020555555555556

= 0.14337208778404

= 0.143374

Standard Deviation = 0.143374

Coefficient of Variation for Security Service Company:

CV = (Standard Deviation / Mean) * 100%

     = (0.143374 /  1.55) * 100

     = 0.09249935 * 100

     = 9.249935

CV  = 9.2

CV  = 9.2%

Calculate Mean for Other Companies data:

Mean =  (Σ x₂) / n₂

          =  (1.8 + 1.9 + 1.6 + 1.7 + 1.8 + 1.9 + 1.6 + 1.5 + 1.7 + 1.8) / 10

          =   17.3 / 10

Mean  = 1.73

Calculate Standard Deviation for Other Companies data:

Standard Deviation = √∑(x₂-Mean)²/n₂-1

                                = √∑[(1.8-1.73)² + (1.9-1.73)² + (1.6-1.73)² + (1.7-1.73)² + (1.8-1.73)² + (1.9-1.73)² + (1.6-1.73)² + (1.5-1.73)² + (1.7-1.73)² + (1.8-1.73)²] / 10 - 1

                                = √∑ [(0.07)² + (0.17)² + (-0.13)² + (-0.03)² + (0.07)² + (0.17)² + (-0.13)² + (-0.23)² + (-0.03)² + (0.07)²] / 9

                                = √∑ (0.0049 + 0.0289 + 0.0169 + 0.0009 + 0.0049 + 0.0289 + 0.0169 + 0.0529 + 0.0009 + 0.0049) / 9

                                = √(0.161 / 9)

                                = √0.017888888888889                                

                                = 0.13374935098493

                                =  0.13375

Standard Deviation = 0.13375

Coefficient of Variation for Other Companies:

CV = (Standard Deviation / Mean) * 100%

     = (0.13375 / 1.73) * 100

     = 0.077312 * 100

     = 7.7312

CV = 7.7

CV = 7.7%

Yes, the limited data listed here shows evidence of stealing by the security service​ company's employees because there is a significant difference in the variation.

What is the measure of FEG?

A. 30 degrees

B. 40 degrees

C. 50 degrees

D. 70 degrees

Please include ALL work!! <3

Answers

Answer:

C. 50 degrees

Step-by-step explanation:

Because 6x + 5x = 110° and x = 10

5×10 = FEG 50°

A human factor expert recommends that there be atleast 9 square ft of floor space in a classroom for every student in the class. Find the min space required for 49 students

Answers

I think the answer is 441 ft I’m sorry if it’s wrong

A car enters a turnpike 22 miles north of a town. The car teavels north at an average speed of 64 miles per hour. How far is the car from the town after 4 hours? Explain how you can use linear function to solve this problem. Then, solve the problem.​

Answers

Answer:

distance traveled can be modeled by a linear functionthe car is 260 miles north of town

Step-by-step explanation:

a) When the speed is constant, the distance traveled is proportional to the travel time, a linear relationship. The distance traveled can be added to the initial distance to obtain the total distance (from town). This relation is a linear function. It can be modeled by the equation ...

  d(t) = 4 + 64t . . . where t is travel time in hours, d(t) is the distance in miles

b) After 4 hours, the distance north of town is ...

  d(4) = 4 +64(4) = 260

The car is 260 miles from the town after 4 hours.

Answer: Distance is a function of time. The constant rate of change is 64. Write the equation y = 64x + 22. Substitute 4 in for x to get 278 miles.

Step-by-step explanation:

Chloe wants to wrap a present in a box for Sarah. The top and bottom of the box is 8 in. by 3 in., the sides are both 3 in by 2 in. and the front and back are 8 in by 2 in. How much wrapping
paper will Chloe need to wrap the present?

Answers

Answer:

92 inches squared

Step-by-step explanation:

T/P = 8 * 3

L/R = 3 * 2

F/B = 8 * 2

Solving for surface area!

2(24) + 2(6) + 2(16) = 92

Carla drove her truck 414 miles on 18 gallons of gasoline. How many miles did she drive per gallon?

Answers

Answer:

23 miles per gallon

Step-by-step explanation:

414 miles = 18 gallons

=> 18/18 gallons = 414/18 miles

=> 1 gallon = 23 miles

So, she drove 23 miles per gallon.

Find an exact value of sin(17pi/12)

Answers

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   Hi my lil bunny!

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[tex]\frac{(17)(3.141593)}{12}[/tex]

= [tex]\frac{53.407075}{12}[/tex]

= [tex]4.45059[/tex]

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If this helped you, could you maybe give brainliest..?

Also Have a great day/night!

❀*May*❀

I have an answer and explanation but I can't type so search up the question you asked and you should get an answer and explanation from s0cratic.

If the discriminant of a quadratic equation is equal to -8 , which statement describes the roots?

Answers

Answer: There are no real number roots (the two roots are complex or imaginary)

The discriminant D = b^2 - 4ac tells us the nature of the roots for any quadratic in the form ax^2+bx+c = 0

There are three cases

If D < 0, then there are no real number roots and the roots are complex numbers.If D = 0, then we have one real number root. The root is repeated twice so it's considered a double root. This root is rational if a,b,c are rational.If D > 0, then we get two different real number roots. Each root is rational if D is a perfect square and a,b,c are rational.

Scores on a college entrance examination are normally distributed with a mean of 500 and a standard deviation of 100. What percent of people who write this exam obtain scores between 350 and 650?

Answers

Answer:

The percentage is [tex]P(350 < X 650 ) = 86.6\%[/tex]

Step-by-step explanation:

From the question we are told that

   The population mean is  [tex]\mu = 500[/tex]

     The standard deviation is  [tex]\sigma = 100[/tex]

The  percent of people who write this exam obtain scores between 350 and 650    

    [tex]P(350 < X 650 ) = P(\frac{ 350 - 500}{ 100} <\frac{ X - \mu }{ \sigma } < \frac{650 - 500}{ 100} )[/tex]

Generally  

               [tex]\frac{X - \mu }{\sigma } = Z (The \ standardized \ value \ of \ X )[/tex]

   [tex]P(350 < X 650 ) = P(\frac{ 350 - 500}{ 100} <Z < \frac{650 - 500}{ 100} )[/tex]

   [tex]P(350 < X 650 ) = P(-1.5<Z < 1.5 )[/tex]

   [tex]P(350 < X 650 ) = P(Z < 1.5) - P(Z < -1.5)[/tex]

From the z-table  [tex]P(Z < -1.5 ) = 0.066807[/tex]

   and [tex]P(Z < 1.5 ) = 0.93319[/tex]

=>    [tex]P(350 < X 650 ) = 0.93319 - 0.066807[/tex]

=>  [tex]P(350 < X 650 ) = 0.866[/tex]

Therefore the percentage is  [tex]P(350 < X 650 ) = 86.6\%[/tex]

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