An investigator wishes to estimate the mean number of flight hours of pilots who fly for regional airlines. Assuming that the standard deviation of the number of hours is 120 hours, the minimum sample size needed in order to construct a 99% confidence interval for the mean number of hours of flight time of all such pilots, to within 50 hours, is about

Answers

Answer 1

Answer:

The minimum sample size needed is 39.

Step-by-step explanation:

We have that to find our [tex]\alpha[/tex] level, that is the subtraction of 1 by the confidence interval divided by 2. So:

[tex]\alpha = \frac{1 - 0.99}{2} = 0.005[/tex]

Now, we have to find z in the Ztable as such z has a pvalue of [tex]1 - \alpha[/tex].

That is z with a pvalue of [tex]1 - 0.005 = 0.995[/tex], so Z = 2.575.

Now, find the margin of error M as such

[tex]M = z\frac{\sigma}{\sqrt{n}}[/tex]

In which [tex]\sigma[/tex] is the standard deviation of the population and n is the size of the sample.

Assuming that the standard deviation of the number of hours is 120 hour

This means that [tex]\sigma = 120[/tex]

The minimum sample size needed in order to construct a 99% confidence interval for the mean number of hours of flight time of all such pilots, to within 50 hours, is about?

The minimum sample size needed is n.

n is found when [tex]M = 50[/tex]

So

[tex]M = z\frac{\sigma}{\sqrt{n}}[/tex]

[tex]50 = 2.575\frac{120}{\sqrt{n}}[/tex]

[tex]50\sqrt{n} = 2.575*120[/tex]

[tex]\sqrt{n} = \frac{2.575*120}{50}[/tex]

[tex](\sqrt{n})^2 = (\frac{2.575*120}{50})^2[/tex]

[tex]n = 38.19[/tex]

Rounding up

The minimum sample size needed is 39.


Related Questions

HURRY FAST LOOK AT THE PHOTO TRUE OR FALSE

Answers

That is true. 4 and 5 are corresponding angles.

What is the area of this semicircle if the radius is 6m?

Answers

Semicircle = half area of circle
Area of circle: pi * r^2
pi = 3.14, r = 6
3.14 * 6^2 = 113.04/2 = 56.52
The area of the semicircle is 56.52 m^2

What is a good estimate for this angle measurement? A. 10 degrees B. 25 degrees C. 75 degrees D. 95 degrees

Answers

Answer:

C. 75 degrees

Step-by-step explanation:

Answer:

75

Step-by-step explanation:

guys i guessed

Use triangle DEF shown below to answer the question that follows. What is the value of X rounded to the nearest hundredth?

Answers

Answer:

it might be x=63.27

Step-by-step explanation:

Question 6 of 10
What is the equation of the following line? Be sure to scroll down first to see
all answer options.
10 T. (1.9)
-10
(0, 0)
10
-101
O A. y=-*
O B. y= 18x
O C. y=9x
O D. y= -18x
1
X
O E. y = 5
O F. y=-9x
SUBMIT

Answers

The equation for the following line is E.

The equation of the line is y = 9x. The correct answer is C.

What is an equation?

An equation is an expression that shows the relationship between two or more numbers and variables.

A mathematical equation is a statement with two equal sides and an equal sign in between. An equation is, for instance, 4 + 6 = 10. Both 4 + 6 and 10 can be seen on the left and right sides of the equal sign, respectively.

We are given that;

the points of line are (1,9) and (0,0).

Now,

In this case, the given points are (1, 9) and (0, 0). We can use them to find the slope:

m = (y2 - y1) / (x2 - x1) m = (0 - 9) / (0 - 1) m = -9 / -1 m = 9

Then we can use the point-slope form with any of the given points. Let’s use (0, 0):

y - y1 = m (x - x1) y - 0 = 9 (x - 0) y = 9x

This is already in slope-intercept form. The slope is 9 and the y-intercept is 0.

Therefore, the equation of the line will be y = 9x.

Learn more about equations here;

https://brainly.com/question/25180086

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I need some help! I would really appreciate it!

Answers

Answer:

answer is A

Step-by-step explanation:

slope goes up positive 4 and it crosses the y intercept at 3 so yeg there ya go ig

I need help answering this question above! Nobody is answering it

Answers

Answer:

(54, 27)

Step-by-step explanation:

2y will represent the larger number.

2y + y = 81

3y = 81

y = 27

x = 2y

x = 2(27)

x = 54

x = 54

y = 27

(54, 27)

Unit 10: Circles ** please show how you got the answer ** i know the answer is 108° but i don’t know how to get it.

Answers

Answer:

108 degrees

Step-by-step explanation:

you gotta add the degrees up with a protractor or you add 54 plus 54 which equals 108

3.65 is greater than or less than 3and1/5​

Answers

3.65 is greater than 3 1/5 since if you put 1/5 in decimals, it would be 3.20.

Answer:

Greater

Step-by-step explanation:

It is greater because 3 & 1/5 is technically 3.20 which obviously results with 3.65 being greater than 3.2. Also if you go into detail with it 3.65 is kinda 3 & 3/5. Thanks. Let me know if you find any fault in my answer. Have a good day!

Math 3rd grade can anyone explain why is 48 ?? I thought that we need to plus 6 top 6 bottom and each side is 8 why 8 because 6+2 is 8
So 6+6+8+8 = 24

Answers

Answer:

It's 48

Step-by-step explanation:

The entire area of the rectangle would be length times width

The width is six, and the length is 8

6 times 8 is 48

btw, its asking for area

Answer:

See, its divided into TWO squares/rectangles.

you have to solve with the numbers you have on each one.

so, for the covered in shade one, you do 6 times 2, which is 12.

for the "not covered" you need to find the second number for the square. Since it has equal sides, the other side will be 6.

for that one you do 6 times 6 which is 36.

now you add both of them.

36 + 12= 48.

You added them, you need to multiply them but do not mix both rectangles/ squares numbers  until the end

Select ALL TRUE statements about Linear Functions:
Group of answer choices

The degree of the function is one.

The y values change by a common difference.

The graph is a straight line.

Vertex form is used for graphing.

Answers

Step-by-step explanation:

The degree of the function is one: Correct

The y values change by a common difference: incorrect

The graph is a straight line: Correct

Vertex form is used for graphing: Incorrect

Hope that helps :)

17.
Which pair of numbers is relatively prime? *


7 & 21
4 & 15
ОООО
6 & 9
9 & 27

Answers

Answer:

9 & 27

Step-by-step explanation:

since all prime numbers above 5 end in 1,3,7 and 9then to find a prime number between say 70 and 80 the only possibilities are 71,73,77,79

Answer:

9 & 27

Step-by-step explanation:

Plz mark as Brainliest...

Help please !! need it adap

Answers

Answer:

m < Q = 40°

m < M = 60°

Step-by-step explanation:

1.) All angles in every triangle altogether equal 180°

From the 4 measurements, you can tell angle Q and S are equal in order to make all angles equal 180 and those angles to be equal (below)

180 - 100 = 80

80/2 = 40

2.) This is an isoceles  (all angles and sides are equal) There are three angles (divide 180 by 3)

180/3 = 60

A retiree invests $7,000 in a savings plan that pays 7% per year. What will the account balance be at
the end of the first year?

Answers

Answer:

$6510

Step-by-step explanation:

First thing that should come to mind is: What is 7% of $7000?

Well, if you don't know how to find a percent of something, this is the formula you use:

7000 x 0.07 = 490.

In the first year, they will receive 490 out of the 7000 they've invested.

7000 - 490 = 6510.

Therefore, the account balance at the end of the first year will be 6510.

The account balance at the end of first year will be equal to $6510.

What do you mean by percentage ?

Percentage is the relative value indicating one hundredth part of any quantity.

It is given that a retiree invests $7000 in a savings plan which pays 7% per year.  So , it meant that we need to calculate that what is the value 7% of $7000.

So , 7% of $7000 is :

= 7000 × [tex]\frac{7}{100}[/tex]

= $490

It is known that this amount is paid as per plan per year. So, to find out the account balance at the end of the first year , we need to subtract the invested amount to the amount per year at 7%.

So , the account balance at the end of first year will be :

= 7000 - 490

= $6510

Therefore , the account balance at the end of first year will be equal to $6510.

Learn more about percentage here :

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What is the area of the following figure in square inches?

Answers

Answer, Alright the formula for a Rectangle is (A = bh) so ill do ( 13 x 8 ) = 104. Next ill do the triangle 19 - 13 is 6 which is the height of the triangle. The formula for a triangle is ( 1/2bh ) so lets do (6 x 8 ) which is 48 now lets divide it by 2...24.

24 + 104 = 128

Step-by-step explanation:

First, I split the Square from the Traingle

Second, I did base times height which equaled  (104)

Third, I found the area of the triangle by base times height divided by 2.(24)

Lastly, I added the figures up which equaled 128

PLEASE ANSWER ASAP WILL MARK BRAINLIEST!!!

Evaluate f^-2 g for f = 3 and g = 27.

a) 9

b) 1/3

c) 3

Answers

B because it looks like it

(3)^-2 (27)

the answer is C) 3

Will give brainliest

Find the area of this triangle.
Round to the nearest tenth.
7 in
133
13 in
[ ? ) in2

Answers

Answer:

33.3 in²

Step-by-step explanation:

Apply the formula for finding the area of triangle that has an included angle and two given sides, which is, Area = ½*a*b*Sin*C

Where,

a = 7 in

b = 13 in

C = 133°

Plug in the values

Area = ½*7*13*Sin(133)

Area = 33.2765935 ≈ 33.3 in² (nearest tenth)

are these correct???

Answers

Answer:

They are all correct.

Step-by-step explanation:

1.

1/2(b)(h)

1/2(4)(6)

1/2(24)

12

2. l x w

7 x 5

35

3. (b)(h)

(8)(4)

32

P=(L+B), then B=_____?

Answers

Answer:

P = L+B

B = P-L

Hope it helps

Professor Gym conducts a study in which he determines that there is a correlation of​ +1.32 with 15 degrees of freedom between the speed of a dodge ball and the welt inflicted on the arm of the dodge ballers. He has now come to you for help with interpreting his results. What can you tell​ him?

Answers

Answer:

Formula

r =\frac{\sum\left(x_{i}-\bar{x}\right)\left(y_{i}-\bar{y}\right)}{\sqrt{\sum\left(x_{i}-\bar{x}\right)^{2} \sum\left(y_{i}-\bar{y}\right)^{2}}}

r = correlation coefficient

x_{i} = values of the x-variable in a sample

\bar{x} = mean of the values of the x-variable

y_{i} = values of the y-variable in a sample

\bar{y} = mean of the values of the y-variable

now try btw use a calcutator

I have no clue how to do this! please help me!!!

Answers

Answer:

The equation has one solution.

A value of x that makes the equation true is 5, which when substituted into the equation and simplified makes the equation turn into 10=10

A value of x that makes the equation false is 6, which when substituted into the equation and simplified makes the equation turn into 12=10

Step-by-step explanation:

2x=10

Divide both sides by two:

2x/2=10/2

x=5. There is no other solution to the equation, because 5 is the only possible answer.

What is the name of the object pictured below?

Answers

Answer:

b

Step-by-step explanation:

Answer: D) KJ

Step-by-step explanation:

The object shown is a ray. It has a fixed starting point, but does not have an endpoint.

56 + 72 = ( + )
help plz

Answers

Answer:

128 = +

Step-by-step explanation:

56 + 72  = 128 (+)

I can't figure this problem out- Please help me​

Answers

Answer:

68 in^2

Step-by-step explanation:

the shape is a trapezoid

A trapezoid is a convex quadrilateral. A trapezoid has at least on pair of parallel sides. the parallel sides are called bases while the non parallel sides are called legs

Characteristics of a trapezoid

It has 4 vertices and edges

If both pairs of its opposite sides of a trapezoid are parallel, it becomes a parallelogram

Area of a trapezoid =   x (sum of the lengths of the parallel sides) x height

the dimension of the height is not given. We have to determine the value of the height using Pythagoras theorem

The Pythagoras theorem : a² + b² = c²

where a = length

b = base

c =  hypotenuse

10² = 6² + height²

100 = 36 + height²

height = 64

the square root of 64 is 8

the height is 8

1/2 x (8 + 9) x 8 = 68in^2

Select all numbers that have and absolute value of 0.6

Answers

I needed help on this... Answer:
l-0.6l and 0.6 and l 0.6 l
Step-by-step explanation:
a number in l x l for is to be changed to positive if not already!

Please answer soon!!!

Answers

You can multiply the base times the height

What is the range of y=4sin(x)-2

Answers

Answer:

According to me it should be -6 [tex]\leq[/tex] y [tex]\leq[/tex] 2.

Step-by-step explanation:

Omlll, I'm actually stuck rn xD If anyone can help,i'd appreciate it so much!! Tyssmm!!!!!

Answers

Answer: it’s acute

Step-by-step explanation:

the second one lollollol

Anna charges $8.50 an hour to babysit how long will it take to make $51.00

Answers

Answer:

6 hours

Step-by-step explanation:

$51.00 ÷ $8.50 = 6 hours

hope this helps ! :))



Someone actually help me w this ☝

Answers

Answer

Sorry If this is not correct, but I believe you keep the X varriable the same and multiply the Y varriable by 4. This means it will move to the right on the grid.

New coordinates: G(3,4) T(1,4) B(3, 20)

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