The lifetime of a certain brand of battery is known to have a standard deviation of 9 hours. Suppose that a random sample of 90 such batteries has a mean lifetime of 38.9 hours. Based on this sample, find a 90% confidence interval for the true mean lifetime of all batteries of this brand.

Answers

Answer 1

Answer:

lower limit : 36.44

upper limit : 39.56

Step-by-step explanation:

Given :

s = 9

n = 90

x = 38.9

Alpha, α = 0.10

∴ [tex]$z_{\alpha/2}=z_{0.05} = 1.645$[/tex]

The confidence interval is :

[tex]$=x \pm\left(z_{\alpha /2} \times \frac{s}{\sqrt{n}}\right)$[/tex]

[tex]$=38.9 \pm\left(1.645 \times \frac{9}{\sqrt{90}}\right)$[/tex]

[tex]$=38.9 \pm 1.56$[/tex]

[tex]$=(36.44, 39.56)$[/tex]

Therefore,

lower limit : 36.44

upper limit : 39.56


Related Questions

The function rule C = 40n + 210 relates the number of months n to cost in dollars C of a phone plan and budget phone. Make a table of the input/output pairs to show the cost of the phone and phone plan after 2, 12 and 24months

(Please help. I need this)

Answers

Answer:

Input - Output

2 - $290

12 - $690

24 - $1170

Step-by-step explanation:

Cost after n months:

The cost after n months is given by the following function:

[tex]C(n) = 40n + 210[/tex]

After 2 months:

This is C(2). So

[tex]C(2) = 40(2) + 210 = 80 + 210 = 290[/tex]

After 12 months:

This is C(12). So

[tex]C(12) = 40(12) + 210 = 480 + 210 = 690[/tex]

After 24 months:

This is C(24). So

[tex]C(24) = 40(24) + 210 = 960 + 210 = 1170[/tex]

Table:

Input - Output

2 - $290

12 - $690

24 - $1170

cho p(A)=0,5 ; p(B) = 0,3 ;p(A∩B)=0,2. Tính p(B∪A) ?

Answers

Answer:

.6

Step-by-step explanation:

BUA= A+B-A∩B

.5+.3-.2= .6

The should be answer is .6

In parallelogram JKLM if m

Answers

Answer:

155 degree

Step-by-step explanation:

x + 25 = 180 degree (sum of adjacent angles of a parallelogram are equal)

x = 180 - 25

x = 155 degree

Tom and his four friends are going to a baseball game. If the total amount they spent on tickets was $50, how much did they spend on each ticket?

Answers

12.50 on each ticket

Step-by-step explanation:

12.50 x 4 = 50.00

Find the area of the figure round to the nearest tenth

Answers

Answer:

Area of given figure = 60.8 mm² (Approx.)

Step-by-step explanation:

Given:

Length of figure = 9.3 mm

Width of figure = 7.8 mm

Height of triangular cut = 3 mm

Find:

Area of given figure

Computation:

Area of given figure = [(Length)(Width)] - Area of triangle

Area of given figure = [(9.3)(7.8)] - [(1/2)(b)(h)]

Area of given figure = [(9.3)(7.8)] - [(1/2)(7.8)(3)]

Area of given figure = [(9.3)(7.8)] - [(1/2)(7.8)(3)]

Area of given figure = [72.54] - [(1/2)(7.8)(3)]

Area of given figure = [72.54] - [11.7]

Area of given figure = 60.8 mm² (Approx.)

7056 plants are to be planted in a garden in such a way that each row contains as many plants as the number of rows and the number of plants in each row​

Answers

Answer:

84 rows

84 plants on each row

Step-by-step explanation:

Given

[tex]Plants = 7056[/tex]

Required

The number of rows

Since the number of rows (r) and the plants on each row (p) are the same, then the area to be planted on is:

[tex]Plants = r * p[/tex]

Where

[tex]r =p[/tex]

So, we have:

[tex]Plants = r * r[/tex]

[tex]Plants = r^2[/tex]

This gives:

[tex]7056 = r^2[/tex]

Take square roots

[tex]84 = r[/tex]

Rewrite

[tex]r = 84[/tex]

A pizza has a radius of 7 inches. If it is cut into 6 equal slices, what is the area of each slice?

Answers

answer: each slide would be one sixth of the entire area; the entire area is (pi)(72).  

Do not use pi = 22/7 because that's untrue. It's approximately 3.1416; round off later!

hope this helps

First we need to find the area of the circle. The formula for the area of the circle is the radius squared times pi. So the entire area would be 49 pi. Then divide 49pi by 6. That is 8 1/6 pi. Then you can plug pi in. So the answer is approximately 25.6563400043

calculate 3ab + b for a=2 and b=-3

Answers

Your answer will be -21 as it’s 3x2x-3-3=21

What is the area of a regular hexagon (6 sides) whose
ℎ ℎ 6 ℎ ℎ ℎ ℎ 3√3 ? Show work
A) 54√3 2
B) 36√3 2
C) 108√3 2
D) 18√3 2

Answers

Step-by-step explanation:

With reference to the regular hexagon, from the image above we can see that it is formed by six triangles whose sides are two circle's radii and the hexagon's side. The angle of each of these triangles' vertex that is in the circle center is equal to 360∘6=60∘ and so must be the two other angles formed with the triangle's base to each one of the radii: so these triangles are equilateral.

The apothem divides equally each one of the equilateral triangles in two right triangles whose sides are circle's radius, apothem and half of the hexagon's side. Since the apothem forms a right angle with the hexagon's side and since the hexagon's side forms 60∘ with a circle's radius with an endpoint in common with the hexagon's side, we can determine the side in this fashion:

tan60∘=opposed cathetusadjacent cathetus => √3=Apothemside2 => side=(2√3)Apothem

As already mentioned the area of the regular hexagon is formed by the area of 6 equilateral triangles (for each of these triangle's the base is a hexagon's side and the apothem functions as height) or:

Shexagon=6⋅S△=6(base)(height)2=3(2√3)Apothem⋅Apothem=(6√3)(Apothem)2

=> Shexagon=6×62√3=216

please helppppppppp me​

Answers

So there was a total of 28 games played and the Houston Tigers only scored above 53 points 4 times. Now the fraction would be 4/28 but we have to reduce so the real answer is actually 1/7

Does anyone know the answer to this?

Answers

If h = hourly rate and s = service fee
2h + s = 180
3h + s = 230
Subtracting equation 1 from equation 2 gives
h = 50
Substitute for h in equation 1
2 x 50 + s = 180
So s = 80

The cost formula is C(h) = 50h + 80

Marking brainliest(for correct answers)


Factor completley:
9(x-1)-(x-1)^2

Answers

- (x-1) (x-10)
hope this helps

A store only sells 20-pound bags of ice. Over the weekend, the store sells 800 bags of ice, making $3,400. On Monday, the store sells 80 bags of ice. How much money does the store make selling ice on Monday?

Answers

£3400 / 800 bags of ice
= £4.25 per bag

80 X £4.25 = £340

The amount of money the store makes selling ice by the same ratio will be $340.

What are the ratio and proportion?

The ratio is the division of the two numbers.

For example, a/b, where a will be the numerator and b will be the denominator.

Proportion is the relation of a variable with another. It could be direct or inverse.

As per the given,

The store sells 800 bags of ice, making $3,400.

Ratio = 3400/800

With the same ratio,

The store sells x amount of bags of ice,

x/80 = 3400/800

x = $340

Hence "The store will make $340 from selling ice using the same ratio".

For more information about ratios and proportions,

brainly.com/question/26974513

#SPJ2

Mark is hosting a "Who Dunnit?" party at his house. He plans on taping off a triangular section of his backyard to represent the crime scene. If the sides measure 23 feet, 15 feet, and 32 feet, how much tape will be needed? DO NOT ANSWER JUST TO STEAL MY POINTS!!

Answers

Answer:

70 feet

Step-by-step explanation:

Given

[tex]Sides: 23ft, 15ft, 32ft[/tex]

Required

The tape needed

This implies that we calculate the perimeter (P)

This is calculated as:

[tex]P = \sum sides[/tex]

So:

[tex]P = 23ft +15ft + 32ft[/tex]

[tex]P = 70ft[/tex]

Answer:

dude why does it say your in college?!?

Step-by-step explanation:

Also I DON'T KNOW just kidding um before some fork tard deletes my answer Hi how are you????

HELP ME PLS I SUCK AT MATH I NEED ANSWER ASAP

Answers

A) -3+4 = -1
B) 5-3= 2
C) 15-7=8
D) 8-3=5
E) +12-5=7

Amy has a bag with 2 pink marbles and 3 purple marbles. She picks two marbles. How much greater is the probability of Amy picking two consecutive pink marbles if she replaces her first marble as opposed to her leaving the first marble she picks out of the bag?

Answers

Answer:

2/5 is the answer bc there are 5 total marbles and you have more purple marbles then pink ones so the answer is 2/5 or 40%

A shoreline observation post is located on a cliff such that the observer is 280 feet above sea level. The observer spots a ship approaching the shore and the ship is traveling at a constant speed.

Requried:
a. When the observer initially spots the ship, the angle of depression for the observer's vision is 6 degrees. At this point in time, how far is the ship from the shore?
b. After watching the ship for 43 seconds, the angle of depression for the observer's vision is 16 degrees. At this point in time, how far is the ship from the shore?

Answers

Using the slope concept, it is found that the distances from the shore at each moment are given by:

a) 2664 feet.

b) 976 feet.

What is a slope?

The slope is given by the vertical change divided by the horizontal change, and it's also the tangent of the angle of depression.

Item a:

The vertical distance is of 280 feet, with an angle of . The distance from the shore is the horizontal distance of x. Hence:

[tex]\tan{6^\circ} = \frac{280}{x}[/tex]

[tex]x = \frac{280}{\tan{6^\circ}}[/tex]

x = 2664.

Item b:

The vertical distance is of 280 feet, with an angle of 16º. The distance from the shore is the horizontal distance of x. Hence:

[tex]\tan{16^\circ} = \frac{280}{x}[/tex]

[tex]x = \frac{280}{\tan{16^\circ}}[/tex]

x = 976.

More can be learned about the slope concept at https://brainly.com/question/18090623

0.135 written as a fraction is

Answers

Answer:

[tex] \frac{27}{200} [/tex]

Step-by-step explanation:

Convert to a mixed number by placing the numbers to the right of the decimal over 1000. Reduce the fraction.

Hope it is helpful...

the two solids below are similar and the ratio between the lengths of their edges is 4:7 what is the ratio of their surface areas? A 7:4 B 16:49 C 16:29 B 64:343

Answers

9514 1404 393

Answer:

  B.  16:49

Step-by-step explanation:

The area ratio is the square of the edge length ratio:

  area ratio = (4:7)² = 4²:7² = 16:49

_____

It might help you to recall that area is the product of two linear dimensions if each is multiplied by 4/7, the resulting product will be multiplied by (4/7)².

  A = LW

  A' = (4/7L)(4/7W) = (4/7)²(LW) = (16/49)·A

Can y’all help me on question 6?!

Answers

Answer:

B

Step-by-step explanation:

To find the area of a parallelogram you do A=(b)(h) so 20x8=160. It's 160ft^2 because area is measured in square units.

I believe the answer would be B. 160ft^2

Since you are looking for area, you need the little 2 at the end to signify that it is squared feet, so that eliminated A and C

Now, the area for a parallelogram is base(height) so it would be 20(8) which is 160

Since we have previously eliminated A and C for not having the feet squared, it would be B

Please correct me if I am wrong, have a good day!


Ezra had 46 green marbles. Then he bought 6 bags of blue marbles. There were 8 marbles in
each bag. How many marbles does Ezra have now?
marbles

Answers

Answer:

94 marbles

Step-by-step explanation:

46 green marbles + (6 bags x 8 pieces of marbles) = 94 marbles

TRIGONOMETRY (RIGHT ANGLE) PLEASE HELP

Answers

Answer:

x = 41.05

Step-by-step explanation:

Given that,

In a right angles triangle,

Perpendicular height, P = 228

Angle 1 = 90°

Angle 2 = 47°

Angle 3 = 180-(90+47) = 43°

Using trigonometry to find x.

[tex]\sin\theta=\dfrac{P}{x}\\\\x=\dfrac{P}{\sin\theta}\\\\x=\dfrac{28}{\sin(43)}\\\\x=41.05[/tex]

So, the value of x is equal to 41.05.

I have a linear equation word problem pic to follow ​

Answers

Yes, go ahead , where is pic?

HELPPP PLEASEEESSS

Which best describes the triangle?
acute and scalene
80
right and isosceles
6 in.
6 in.
1)) obtuse and isosceles
50°
50°
7.7 in.
acute and isosceles

Answers

Answer:

acute and isosceles

Step-by-step explanation:

Define:

Acute - All angles have a measure of less than 90 degrees

Obtuse - has an angle with a measure of more than 90 degrees

Right - has an angle with a measure of 90 degrees

Scalene - no congruent side lengths or angles

Isosceles - two congruent sides and two congruent angles

Equilateral - all congruent sides and all congruent angles

Identify:

The triangle shown has angles that measure less than 90 degrees which means that it's an acute triangle

The triangle also has two congruent sides and two congruent angles which means that it's an isosceles triangle.

So we can conclude that the triangle can be identified as an acute isosceles

A researcher uses an independent-measures t test to evaluate the mean difference between two treatments and obtains t(12) = 4.00. If the researcher had used an ANOVA to evaluate the data, what F-ratio would be obtained?

a. F(1, 11) = 2.00
b. F(1, 12) = 16.00
c. F(1, 12) = 2.00
d. F(1, 11) = 16.00

Answers

Answer:

B). F(1, 12) = 16.00

Step-by-step explanation:

'ANOVA' is a measure employed for 'analysis of a variance' in a given set of data of treatments or populations. While t-test helps in comparing their means.

As per the question, the F-ratio using ANOVA would be 'F(1, 12) = 16.00.' In order to calculate the variances, the distinction among the samples. The б^2 denotes the difference of representative means which is augmented by n(in case of samples being same). So, the ratio of F(1, 12) would be б^2 i.e. 4^2 = 16 since the sample sizes are distinct. Thus, option B is the correct answer.

Determine if the sequence below is arithmetic or geometric and determine the
common difference / ratio in simplest form.
100, 20, 4, ...

Answers

Answer:

its a geometric progression. r=1/5 or 0.2

Which conditional statement is represented by the Venn diagram below?
Quadrilateral
Square
A. If a shape is a square, then it is a quadrilateral.
B. If a shape is a square, then it is not a quadrilateral.
0
C. If a shape is a quadrilateral, then it is a square.
D. If a shape is a quadrilateral, then it is not a square.




Answers

The answer is A. If the shape is a square, then it is a quadrilateral.

B is incorrect because a square is a quadrilateral.

C is incorrect because not all quadrilaterals are squares.

D is incorrect because a shape can be square if it’s a quadrilateral.


I hope this helps!

The party planning committee has to determine the number of tables needed for an upcoming event. If a square table can fit 8 people and a round table can fit 6 people, the equation 150 = 8x + 6y represents the number of each type of table needed for 150 people.

The variable x represents the number of

Answers

Answer:

the answer is 25 round tables and you will need 18.75 square tables

Step-by-step explanation:

IT is right trust me

Answer: The variable x represents the number of  

✔ square tables

.

The variable y represents the number of  

✔ round tables

.

If y = 9, find the value of x. The committee needs  

✔ 12

square tables.  explanation:

A dictionary has 88,728 words. Out of that Mohan read 35,427 words. How many words are left for him to read?

Answers

Mohan has 53,301 words left

[tex]\sf \bf {\boxed {\mathbb {Given:}}}[/tex]

Total number of words in the dictionary = 88,728 words

No. of words that Mohan read = 35,427 words

[tex]\sf \bf {\boxed {\mathbb {To\:find:}}}[/tex]

No. of words left for Mohan to read.

[tex]\sf \bf {\boxed {\mathbb {Solution:}}}[/tex]

[tex]\sf\purple{53,301 \:words. }[/tex]

[tex]\sf \bf {\boxed {\mathbb {Step-by-step\:explanation:}}}[/tex]

No. of words left for Mohan to read = Total no. of words in the dictionary - No. of words that Mohan read

= ( 88, 728 - 35, 427 ) words

= 53,301 words

[tex]\large\mathfrak{{\pmb{\underline{\red{Mystique35 }}{\red{❦}}}}}[/tex]

It is reported in USA Today that the average flight cost nationwide is $445.99. You have never paid close to that amount and you want to perform a hypothesis test that the true average is actually greater than $445.99. What are the appropriate hypotheses for this test

Answers

Answer:

[tex]H_0[/tex] : [tex]\mu \leq 445.99[/tex]

[tex]H_a[/tex] : [tex]\mu > 445.99[/tex]

Step-by-step explanation:

It is given the average cost of the flight nationwide is $ 445.99

I wanted to [tex]\text{perform the hypothesis test}[/tex] to determine that the true average is greater than $ 445.99

Let the hypothesis that the true average is actually greater than $445.99

Therefore,

the [tex]\text{null hypothesis}[/tex] for the test is :

[tex]H_0[/tex] : [tex]\mu \leq 445.99[/tex]

And the alternate hypothesis is :

[tex]H_a[/tex] : [tex]\mu > 445.99[/tex]

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