A normal population has the mean of 10 and the variance of 25 . A random sample of size n-28 is selected.
(a) Find the standard deviation of the sample mean. Round your answer to two decimal places (e.g. 98.76)
(b) How large must the sample be if you want to halve the standard deviation of the sample mean?

Answers

Answer 1

Answer:

Step-by-step explanation:

Given that:

population mean = 10

variance [tex]\sigma^2[/tex] = 25  ; [tex]\sigma[/tex] =[tex]\sqrt{ 25}[/tex] = 5

sample size n = 28

The standard deviation of the sample mean:

= [tex]{\dfrac{5}{\sqrt{28}}[/tex]

= 0.95

To halve the standard deviation of the sample mean, the size of how large the sample will be can be computed as follows:

[tex]\dfrac{sd_1}{sd_2} = \dfrac{\dfrac{\sigma}{\sqrt{n}} }{\dfrac{\sigma}{\sqrt{n}} }[/tex]

[tex]\implies \dfrac{\dfrac{5}{\sqrt{28}} }{\dfrac{5}{\sqrt{28}} }[/tex]

[tex]= \dfrac{5}{\sqrt{28}} \times \dfrac{\sqrt{28}}{5}[/tex]

= 2

n = 4 × 28

n = 112

Answer 2

The standard deviation is 0.95 and if the standard deviation is halved then the sample mean is 112.

What is a standard deviation?

It is the measure of the dispersion of statistical data. Dispersion is the extent to which the value is in a variation.

A normal population has a mean of 10 and a variance of 25.

A random sample of sizes n-28 is selected.

A.  The standard deviation will be

[tex]\sigma = \dfrac{\sqrt{Var(x)}}{n} \\\\\sigma = \dfrac{\sqrt{25}}{\sqrt{28}} \\\\\sigma = 0.95[/tex]

B.  The sample be if you want to halve the standard deviation of the sample mean

[tex]\rm \dfrac{SD_1}{SD_2} = 2 = \dfrac{\sqrt{n}}{\sqrt{28}}\\\\n = 4*28 \\\\n= 112[/tex]

More about the standard deviation link is given below.

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Related Questions

10×10×10×10 equals 1,000

Answers

Answer:

yesss it does

Step-by-step explanation:

CONGRATULATIONSSSSS

Answer:

Incorrect

Step-by-step explanation:

10x10x10x10 or 10 to the 4th power has 4 0's and 1,000 only has 3. So, 10x10x10x10=10,000

un angulo θ mide 750° y es coterminal con

Answers

Answer:

El ángulo de 750º es coterminal con los ángulos de 29.88º y 389.88º.

Step-by-step explanation:

Antes de comenzar este enunciado, cabe recordar que dos ángulos en posición estándar son coterminales cuando tiene un lado terminal común, además que el sistema sexagesimal tiene un período de 360º, entonces todo ángulo satisface la siguiente condición:

[tex]\theta = 360\cdot x[/tex], [tex]\forall \,x \in \mathbb{R}[/tex].

Si sabemos que [tex]\theta = 750^{\circ}[/tex], el múltiplo [tex]x[/tex], que indica el número de revoluciones dadas es:

[tex]x =\frac{\theta}{360}[/tex]

[tex]x = \frac{750^{\circ}}{360^{\circ}}[/tex]

[tex]x = 2.083[/tex]

El número de ángulos coterminales equivale al número entero de revoluciones. Y la posición coterminal más pequeña queda determinada por el residuo, que es igual a la diferencia entre el total de revoluciones (2.083) y el número de revoluciones enteras. (2) En este caso, existen dos angulos coterminales cuyas magnitudes determinamos a continuación:

[tex]\theta_{1} = (0 + 0.083)\cdot (360^{\circ})[/tex]

[tex]\theta_{1} = 29.88^{\circ}[/tex]

[tex]\theta_{2} = (1 + 0.083)\cdot (360^{\circ})[/tex]

[tex]\theta_{2} = 389.88^{\circ}[/tex]

El ángulo de 750º es coterminal con los ángulos de 29.88º y 389.88º.

factor the expression 36xyz + 24xy - 16x by dividing each term by a common factor. what are the common possible factors?

Answers

Answer:

4(9xyz+6xy-4x)

Step-by-step explanation:

Since the GCF of all the numbers is 4 you would just divide each term by 4 and make the 4 go outside of the Parenthesis so you get 4(9xyz+6xy-4x)

The common possible factors are 4x and [9yz + 6y - 4] after dividing and multiplying by 4x in the expression.

What is an expression?

It is defined as the combination of constants and variables with mathematical operators.

It is given that:

The expression is:

= 36xyz + 24xy - 16x

As we can see; the common factor in the expression is 4x

The arithmetic operation can be defined as the operation in which we do the addition of numbers, subtraction, multiplication, and division. It has a basic four operators that is +, -, ×, and ÷.

Divide by 4x in the expression and multiply by 4x:

We get:

= 4x[(1/4x)36xyz + 24xy - 16x]

= 4x[9yz + 6y - 4]

Thus, the common possible factors are 4x and [9yz + 6y - 4] after dividing and multiplying by 4x in the expression.

Learn more about the expression here:

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Write the number that represents the decimal Three and five hundreths. Write in decimal

Answers

Answer:

3.05 is the answer.

A small apple weighs 4.5 ounces. if
it is divided into 4 equal Pieces, how
much dose each piece weighs

Answers

Weight of apple = 4.5 ounces

Total pieces = 4

Weight of 1 piece = 4.5 ÷ 4

= 1.125

•°• Each piece weighs 1.125 ounces

Hope it helps

Have a nice day

#BTS army

Which representation shows a proportional relationship between x and y?

Answers

Answer:  D

Step-by-step explanation:

To have a proportional relationship, the value of y divide by x has to have the same constant value and if you were to graph it, it has to go through the origin.

A is not proportional because it is not going through the origin.

B is also not proportional because it is also not going through the origin.

Now to find out if C is proportional divide the y value by x so see if they all have a constant change.

8/2 =4

16/4 = 4

24/8 = 3

32/ 12 = 2.6  

This is also not proportional .

D. 3/2 = 1.5

   6/4 = 1.5

 12/ 8 = 1.5  

 18/12 = 1.5  

This represents a proportional relationship  because they all have a constant change

The proportional relationship between x and y will be given by option D.

What are ratio and proportion?

A ratio is a group of sequentially ordered numbers a and b expressed as a/b, where b is never equal to zero. When two objects are equal, a statement is said to be proportional.

Let's check all the options:

Option A because the line has intercept.

Option B because the line is zero.

Option C:

The slope is given as,

Slope = (16 - 8) / (4 - 2) = 4

Slope = (24 - 16) / (8 - 4) = 2

Slope = (32 - 24) / (12 - 8) = 2

Option D:

The slope is given as,

Slope = (6 - 3) / (4 - 2) = 3/2

Slope = (12 - 6) / (8 - 4) = 3/2

Slope = (18 - 12) / (12 - 8) = 3/2

The proportional relationship between x and y will be given by option D.

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which angles are supplementary to each other?

Answers

option c. ..............

Which number is the smallest? 4.4 ⋅ 10−5, 3.99 ⋅ 10−6, 2.6 ⋅ 102, 1.85 ⋅ 103

Answers

Answer:

3.99 10-6

Step-by-step explanation:

This is simply the answer because if you multiply them all out this equation is the smallest number

Answer:

3.99*10^-6

Step-by-step explanation:

Anything taken to a negative power is going to be smaller than the original number because x^-y=1/(x^y). So since 3.99*10^-6 is smaller than 4.4*10^-5, the former is the answer.

CAN SOMONE PLEASE HELP ME ASAP PLEASEEE!!!​

Answers

Answer:

z = 80°

Step-by-step explanation:

The sum of the interior angles would equal to 360°

100° + 60° + 120° = 280°

360° - 280° = 80°

Answer:

z = 80

Step-by-step explanation:

A quadrilateral has angles that sum to 360°

E + C + G + F = 360

100 + 60 + 120 + F = 360

Combine like terms

280 + F = 360

F = 360 - 280

F = 80

We know that ABCD is similar to FECG

This means that the measure of A = measure of F

z = 80

1/10 is what of 1/100

Answers

Answer:

1/10 = 0.1, 1/100 = 0.01

Step-by-step explanation:

1/10 is 10/100

Answer:One tenth of one hundred is 10 1/10 of 100 = (100 * 1) / 10 = 100 / 10 = 10

Step-by-step explanation:

A solid is composed of squares and equilateral triangles. Its net is shown below: The area of each triangle is 16 square units. The surface area of the triangular prism is _____ square units. (Input whole number only)

Answers

Answer:

12 becayse u mulitigigivuvuu

Show the steps for the merge sort to sort the following values: {199,16,186,115,158,135,186,14,10}

Answers

Answer:

Step-by-step explanation:

STEP 1: Show the array of values.

The array is {199, 16, 186, 115, 158, 135, 186, 14, 10}

STEP 2: Determine the number of elements/values.

Here, it is 9

STEP 3: Starting from zero, assign number tags to each value.

Since the values are 9 in number, the numerical tags will be 0, 1, 2, ..., 8

mv

STEP 3: Check if the sub-array is a base case.

This sub-array has at least 2 figures or values, hence is not a base case.

STEP 4:

What is this called ........................

Answers

Answer:

C

Step-by-step explanation:

Alternate interior angles are next to each other. Sorry if im wrong.

2x – 4y = 24
x + 3y = 7
Solve by elimination

Answers

2x-4y=24
X+3y=7 (-2)


2x-4y=24
-2x-6y=-14
——————-
0 -10y=10
Y=-1

Reemplazar y en la ecuación
2x-4(-1)=24
2x+4=24
2X=20
X=10

Y=-1, X= 10
Hope this helps

A second number is 9 times a first number. A third number is 100 more than the first number. If the sum the three numbers is 694, find the numbers.

Answers

Answer:

54, 486, 154

Step-by-step explanation:

x+9x+100+x= 694

11x= 694-100

11x=594

x= 54

54×9=486

54+100= 154

54+486+154=694.

d is the same as 359 more than the product of 344 and d
write the sentence as an equation ​

Answers

Answer:

d = 359 + 344d

Step-by-step explanation:

d = 359 + 344d

43% of 300 is what number

Answers

129
Find 10% (30) then times by 4 to find 40% (120)
Find 1% (3) then times by 3 to find 3% (9)
Add the 40% to the 3% (120 + 9)
= 129

What is the ordered pair of X' after point X (3, 4) is rotated 180°?

Answers

Answer:

Step-by-step explanation:

the ordered of X' after point X(3,4) rotation 180 degrees is X'(-3,-4)

Answer:

(-3, -4)

Step-by-step explanation:

How do you do this question without looking at the answer choices?

Answers

Answer:

Take a look at the 'proof' below

Step-by-step explanation:

The questions asks us to determine the anti-derivative of the function f(x) = 4x^3 [tex]*[/tex] sec^2 [tex]*[/tex] x^4. Let's start by converting this function into integral form. That would be the following:

[tex]\mathrm{\int \:4x^3sec^2x^4dx}[/tex]

Now all we have to do is solve the integral. Let's substitute 'u = x^4' into the equation 'du/dx = 4x^3.' We will receive dx = 1/4x^3 [tex]*[/tex] du. If we simplify a bit further:

[tex]\mathrm{\int \:\:sec^2\left(u\right)du}[/tex]

Our hint tells us that d/dx [tex]*[/tex] tan(x) = sec^2(x). Similarly in this case our integral boils down to tan(u). If we undo the substitution, we will receive the expression tan(x^4). Therefore you are right, the first option is an anti-derivative of the function f(x) = 4x^3 [tex]*[/tex] sec^2 [tex]*[/tex] x^4.

5
5.
Madeline is making hummus for a potluck. Usually she uses 3 cloves of garlic and
17 ounces of chick peas, but this time she needs to serve more people. If she is
using 68 ounces of chick peas, how many cloves of garlic will she need?
54
12
9
15

Answers

the answer is b (12)

A runner can run 2 miles in 10 minutes. At this rate how many miles can he run in 40 minutes

Answers

Answer:

8 miles

Step-by-step explanation:

At a rate of 2 miles in 10 minutes, in 40 minutes he can run 8 miles.

2 / 10 == x / 40

x == (40 * 2) / 10

x == 8

Cheers.

Answer:

Step-by-step explanation:

8

How to write 4 - 5h in verbal expression

Answers

four minus five times a number

John's electricity bill costs $20.90 per month plus $1.23 per kilowatt hour. How many kilowatt hours can he use and keep his monthly cost no more than $109

Answers

Answer:

71.63 kilowatts hours

Step-by-step explanation:

We are told in the question:

John's electricity bill costs $20.90 per month plus $1.23 per kilowatt hour.

We are to find, How many kilowatt hours can he use and keep his monthly cost no more than $109.

Step 1

$109 - $20.90

= $88.1

$88.1 is the amount left to spend on killowatts of electricity per hour after removing the normal monthly electricity bill in a month

Step 2

$1.23 = 1kilowatts per hour

$88.1 = y kilowatts per hour

Cross Multiply

= $1.23 × y kilowatts per hour = $88.1 × 1 kilowatts per hour

y kilowatts per hour = $88.1 × 1 kilowatts per hour/ $1.23

= 71.62601626kilowatts hour.

Approximately = 71.63 kilowatts hour

Therefore, John can use 71.63 kilowatts per hour and keep his monthly cost no more than $109

Answer:

71

kilowatt hours can he use and keep his monthly cost no more than $109

Which property is illustrated by the following statement? 6 + (x + 8) = ( 6 + x) + 8 Commutative Property of Addition Associative Property of Addition Commutative Property of Multiplication Inverse Property of Addition

Answers

Answer:

Commutative Property of Multiplication, I believe. Hope this helps!

Step-by-step explanation:

Answer:

Associative Property of Addition

On a vacation trip, the smith family traveled 2,648 miles by car to a lake resort on the return trip they took a shorter route and drove 2,023 miles at the end of the trip the car’s odometer read 46,238 miles what did the odometer read at the beginning of the trip

Answers

Answer: 41,567

Step-by-step explanation:

1st: Add 2,648 + 2,023 and get = 4,671

2nd: Subtract 46,238 - 4,671 = 41,567

Describe how you would graph a figure that is translated by (x - 4, y + 2).

Answers

Answer:

see explanation

Step-by-step explanation:

Given the translation rule

(x, y ) → (x - 4, y + 2 )

This means subtract 4 from the original x- coordinate and add 2 to the original y- coordinate, that is

a point (4 , - 4 ) → (4 - 4, - 4 + 2 ) → (0, - 2 )

The resulting graph would result in moving input x by --4  horizontally and Output y by +2 vertically.

What is a translation of a point?

Translations are defined by saying how much a point is moved to the left/right and up/down. Vertically translating a graph is equivalent to shifting the base graph up or down in the direction of the y-axis. A graph is translated k units vertically by moving each point on the graph k units vertically.

Given the point  (x - 4, y + 2), we can clearly observe that the graph would move vertically by +2 units while the input will be in the -ve x-axis direction from right to left and thus will move negatively by -4.

Hence, The resulting graph would result in moving input x by --4  horizontally and Output y by +2 vertically.

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i put a picture and please solve

Answers

Answer: 12.25 or Approximately 12.3

Step-by-step explanation:

To solve this problem, we first need to solve for x. We are given with 2ˣ=7.

To get x alone, we want to use natural log, or ln.

[tex]xln(2)=ln(7)[/tex]         [once you find ln of both sides, you bring the x to the front]

[tex]x=\frac{ln(7)}{ln(2)}[/tex]                 [divide both sides by ln(2)]

[tex]x=2.81[/tex]

We now know that x is approximately 2.81. We can plug that in to find 4ˣ⁻¹.

[tex]4^(^x^-^1^)[/tex]                     [plug in x]

[tex]4^(^2^.^8^1^-^1^)[/tex]                 [parenthesis]

[tex]4^{1.81}[/tex]                        [exponent]

[tex]12.3[/tex]

The answer is approximately 12.3. To get a more exact answer, you would plug in [tex]\frac{ln(7)}{ln(2)}[/tex] into x.

[tex]4^{\frac{ln(7)}{ln(2)}-1 }[/tex]

[tex]12.25[/tex]

The exact answer would be 12.25. This is close to 12.3 since it is rounded up to one decimal place.

Is 1 1/4 a rational number?

Answers

Answer:

Hey there!

1 1/4 is a rational number because it can be expressed as a fraction.

Let me know if this helps :)

What would the answer be to the expression 22 + (30 - 4) ÷2

Answers

Answer:

24

Step-by-step explanation:

Answer:

35

Step-by-step explanation:

22 +(30 - 4) :2

22 +26 :2

22 +13

35

If PQ=11 and QR=12, what is PR

Answers

Answer:

PR = 23

Step-by-step explanation:

Step 1:

PQ + QR = PR

Step 2:

11 + 12 = 23

Answer:

PR = 23

Hope This Helps :)

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