in a survey, 32 people were asked how much they spent on their child's last birthday gift. the results were roughly bell-shaped with a mean of $48 and standard deviation of $7. construct a confidence interval at a 80% confidence level. give your answers to one decimal place.

Answers

Answer 1

The required 80% confidence interval is (46.15, 49.85).

What is a confidence interval?

In frequentist statistics, a confidence interval is a range of estimates for an unknown quantity.

The most common confidence level is 95%, but when calculating confidence intervals, other levels, such as 90% or 99%, are also occasionally employed.

So, we know that:

n = 32

χ' = 48

s = 8

Create an 80% confidence interval using the equation below:

[tex]\left(\bar{X} \pm t_{\frac{\alpha}{2}} \times \frac{s}{\sqrt{n}}\right)[/tex]

To determine the critical value t for n-1 degrees of freedom and 1 -cl level of significance, use the formula below:

[tex]t_{0.2, d f=31}=\pm 1.309[/tex]

Create the confidence interval now:

[tex]\begin{aligned}& \left(48 \pm 1.309 \times \frac{8}{\sqrt{32}}\right) \\& (48 \pm 1.85) \\& (46.15,49.85)\end{aligned}[/tex]

Therefore, the required 80% confidence interval is (46.15, 49.85).

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Related Questions

A marketing research company desires to know the mean consumption of milk per week among people over age 45. They believe that the milk consumption has a mean of 4.2 liters, and want to construct a 98% confidence interval with a maximum error of 0.08 liters. Assuming a standard deviation of 0.6 liters, what is the minimum number of people over age 45 they must include in their sample

Answers

Answer:

The minimum number of people over age 45 they must include in their sample is 305.

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 - 0.98}{2} = 0.01[/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 - 0.01 = 0.99[/tex], so Z = 2.327.

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.

Standard deviation of 0.6 liters

This means that [tex]\sigma = 0.6[/tex]

What is the minimum number of people over age 45 they must include in their sample?

This is n for which M = 0.08. So

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

[tex]0.08 = 2.327\frac{0.6}{\sqrt{n}}[/tex]

[tex]0.08\sqrt{n} = 2.327*0.6[/tex]

[tex]\sqrt{n} = \frac{2.327*0.6}{0.08}[/tex]

[tex](\sqrt{n})^2 = (\frac{2.327*0.6}{0.08})^2[/tex]

[tex]n = 304.6[/tex]

Rounding up:

The minimum number of people over age 45 they must include in their sample is 305.

HELP ASAP A factory makes car batteries. The probability that a battery is defective is is.
If 400 batteries are tested, about how many are expected to be defective?
A. 25
B. 40
C. 16
D. 375

Answers

375 is the ansewer   wwrhttttttttttttttttttt

Answer:

25

Step-by-step explanation:

Please helpppp meeee

Answers

the answer to the question is A

Raymond kept track of the number of hours that he spent practicing the piano each week for several weeks. He spent 2, 4, 8, 6, and 5 hours. What is the range of the data set? B. 5 hours O A. 2 hours O O O D. 6 hours C. 8 hours​

Answers

The answer is D, 6 hours

This graph represents the height a baseball travels in t seconds.

How long is the height of the ball increasing?

0.5 seconds
1 second
2.4 seconds
30 seconds

Answers

We need to see the graph to answer this next time out a picture added
Is their a graph? To answer the question

What is the 20th term of the arithmetic sequence
3, 9, 15, 21, 27, ...?

Answers

Answer: 117

Step-by-step explanation:

first comment on first response!!! Thank you btwww!

IF YOU ANSWER ALL THESE QUESTIONS I WIL LGIVE YOU BRAINIEST AMD 40 POINTS COME UP WITH PROBLEMS THANKS

Answers

Answer:

WHY YOU ARE ALWAYS SAY THAT CAN YOU WHOLE QUESTION..

Select the correct answer.


The figure PQRSTU represents the shape of the parking lot at a shopping mall. What is the area of the parking lot?

A.
834 square feet
B.
918 square feet
C.
984 square feet
D.
1,068 square feet
Reset

Answers

Answer:

Is there an image? I cant figure it out without the image

Step-by-step explanation:

What is the value of 4+2 +6r – tr when t =
=
- 3 and r = 5?
Enter your answer in the box.

Answers

you first substitute your values t and r ...Use BODMAS method ...Your final answer must be 51

2 1/5 + 6 4/5 pls help

Answers

Answer:

2 1/5 + 6 4/5

= 2/5 + 24/5

= 26/5

= 5.2

Answer:

[tex]8\frac{5}{10}[/tex]

Step-by-step explanation:

[tex]2 + 6 = 8\\\frac{1}{5} + \frac{4}{5} = \frac{5}{10}[/tex]

Let me know if this helps!

Brainliest for correct answer

Answers

Answer:

V =1884 in ^3

Step-by-step explanation:

The volume of a cylinder is given by

V = pi r^2 h  where r is the radius and h is the height

V = pi ( 10) ^2 * 6

V = pi ( 600) in^3

Using 3.14  for pi

V = 3.14 * 600 in ^3

V =1884 in ^3

Week 5 Test Taking skills, Page 2
Name
3
Rodrigo bought a sheet of shark stickers. He used 8 of the 32 stickers to decorate his science project about
sharks.
Shark Stickers
DO
How many shark stickers did Rodrigo use on his science project?
A
24
B
18
с
20
D
30

It’s number 3

Answers

Answer:

20

Step-by-step explanation:

5/8 of 32

5/8×32=20

remember of means multiply

HOPE THIS HELP YOU HAVE A NICE DAY OR NIGHT

Find the area of the sector.

Answers

Answer:

D. 158.4 km²

Step-by-step explanation:

Area of sector = θ/360 * πr²

Where,

θ = 150°

r = 11 km

Substitute

Area = 150/360 * π * 11²

Area = 158.38863 ≈ 158.4 km² (nearest tenth)

g Radio and television stations often air controversial issues during broadcast time and ask listeners and viewers to indicate their agreement or disagreement with a given stand on the issue. A poll is conducted by asking those listeners and viewers who agree to call a certain 900 telephone number and those listeners and viewers who disagree to call a second 900 telephone number. All respondents pay a fee for their calls. Does this polling technique result in a random sample

Answers

Answer:

NO, it does not.

Step-by-step explanation:

From the information provided, we know that the surveying method for the polling depends on the no. of calls got on the two sorts of 900 phone numbers.  

This surveying strategy doesn't address a random sample in light of the fact that the viewers who see the show can be restricted. Additionally, among the viewers of the show, the reactions depend on viewers who intentionally approach to offer or air their opinion. Therefore, the acquired sample doesn't address a random sample and specifically, we can posit that the sample occurs to be a voluntary sample.

Help,,,,,,,,,,,,,,,........

Answers

B= 0.5
Because it’s right after A which is 0

https://studio.code.org/projects/flappy/cYGc2S_X9-cgWtBUmJ5BJta5xku7iqyon0wzrKhC-Do

Answers

Answer:

so fun and amazing!

Step-by-step explanation:

It takes Paul 9 hours longer than Li Ming to paint a house. Working together they can do the job in 20 hours. How long would it take Li Ming, working alone, to paint the house ?

Answers

Li Ming can paint the whole house in 10 hours

The mixed number 2 5/6 is equivalent to a fraction with a
denominator of 6.

What is the missing numerator in the equivalent
fraction?

Answers

Answer:

6 x 2 = 12 then add 5, answer is 17

Please help I’ll mark you as brainliest if correct!

Answers

Answer:

B

Step-by-step explanation:

brainliest?

blank plus 1/2 equals to 2/3

Answers

Answer:

1/6 + 1/2 = 2/3

Step-by-step explanation:

Determine whether each ordered pair is a solution of the system of linear equations.
3y = 6x + 12
2x - y = -4
a. (-3,2)
b. (0,4)
a. Is (-3,2) a solution?
0 Yes
Ο Νο
b. Is (0,4) a solution?
O No
0 Yes

Answers

Answer:

(0,4)

Step-by-step explanation:

The given equations are :

3y = 6x + 12  

2x - y = -4

If (-3,2) be the solution of the above equations,

3(2) = 6(-3) + 12

6 = -18+12

6≠ -6  

2x - y = -4

2(2) -(-3) =-4

4+7 = -4

11 ≠ -4

No, (-3,2) is not the solution.

Similarly, put (0,4) in the abve equations,

3(4) = 6(0) + 12

12 = 12

and

2(0) - 4 = -4

-4 = -4

Hence, (0,4) is a solution of the given equations.

PLEASE HELP !!!!!
What is the value of the missing angle?

Answers

Answer:

B

Step-by-step explanation:

180 - 100 = 80

80 = 30 = 110

180 - 110 = 70

Answer:

B

Step-by-step explanation:

100-30=70° Remeber this is a right triangle

help me please I will mark 5 stars please it is urgent

Answers

Answer:

a) 3sec

b) highest point of 50

c) at 0 by 8 sec

A $45 pair of shoes is on sale for 20% off. How much money is saved?

Answers

Answer:

$9

Step-by-step explanation:

Suppose y varies directly with x and inversely with z. If y = 14 when x = 7 and z = 3, what is x when y = 3 and z = 8? Use the step-by-step process you learned to solve this problem.

Step 1: Set up the correct type of variation equation.
y =
✔ kx/z
Step 2: Determine the constant of variation.
k =

Answers

Answer:

The constant of variation k is 6 and the value of x is 4.

Step-by-step explanation:

What is constant of variation?

The constant of variation is the number that relates two variables that are directly proportional or inversely proportional to one another.

What is direct variation?

A direct variation is a proportionality relationship in which two quantities follow a direct relationship.

What is inverse variation?

Inverse variation states when one variable increases then the other variable decreases.

Given,

y=14 when x=7 and z=3

The variation equation is,

y=kx/z

Inputting the values,

14=(k*7)/3

14*3=7*k

42=7k

k=6

When y=3, z=8 we will find x.

y=kx/z

3=6*x/8

3*8=6*x

x=24/6

x=4

Hence, the value is 4.

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Whisper is exercised twice a day.
The first time is for 30 minutes.
The second time is for 11 hours.
i. Write down the fraction of a day that Whisper is exercised.
Write your answer in its simplest form.
ii.
Write down the fraction of a day that she is not being exercised.

Answers

Answer:

I:23/48

ii 25/48

Step-by-step explanation:

30min=0.5hr

total time exercised: 11+0.5=11.5hr

Divided by total hours of a day:

11.5/24=115/240=23/48

ii:(48-23)/48

i. 11.5/24hrs
ii.12.5/24hrs
STEP BY STEP EXPLANATION
1st time = 30 minutes
=0.5hr
2nd time=11hrs
Altogether =11.5hrs
1 day =24hrs
Fraction =11.5/24hrs

ii. Hrs not exercised = hrs in a day - hrs exercised
= 24hrs - 11.5hrs
= 12.5hrs
Fraction of day not exercised = hrs not exercised/hrs of the day
= 12.5/24hrs

Round 329,167 to the nearest hundred

Answers

Answer:

329,200

Step-by-step explanation:

Answer:

329,200

Step-by-step explanation:

What is (14x^2– 27x+9) / (7x-3)?

A. 7x-3
B. 2x-3
C. -211x+9
D. 2x-33

Answers

Answer:

B. 2x - 3

Step-by-step explanation:

[tex] \rm \frac{ {14x}^{2} - 27x + 9}{7x - 3} [/tex]

[tex] \rm = \frac{ \cancel{(7x - 3)}(2x - 3)}{ \cancel{7x - 3}} [/tex]

[tex] \boxed{ \rm \bold{= 2x - 3}}[/tex]

Answer:

[tex]\tt{}2x - 3[/tex]

Step-by-step explanation:

[tex] \tt{} \frac{(14 {x}^{2} - 27x + 9) }{(7x - 3)} [/tex]

[tex] \tt{} \frac{14 {x}^{2} - 6x - 21x + 9 }{7x - 3} [/tex]

[tex]\tt{} \frac{2x \times (7x - 3) - 3(7x - 3)}{7x - 3 } [/tex]

[tex]\tt{}2x - 3[/tex]

500 people are asked if they drink coffee.
9
10 say Yes.
20% of the people who say Yes drink at least three cups each day.
(b)
What fraction of the 500 people drink at least three cups of coffee each
day?
Give your answer in its simplest form.

Answers

Answer:

Step-by-step explanation:

2/10

A satellite system consists of 4 components and can function if at least 2of them are working. If each component independently works with probability 0.8, what is the probability the system will function?

Answers

Answer:

X follows binomial distribution with n=4, p=0.6, q= 0.4. To make the system function adequately, at least 2 components should work well.

Step-by-step explanation:

Hope this helps

Answer:

0.9728

Step-by-step explanation:

We have 2 options for the system to fail - no components work, or only one works.

The probability that no components work is:

[tex]0.2^4 = 0.0016[/tex]

The probability that one SPECIFIC component works and the others failed is:

[tex]0.2^3 \cdot 0.8 = 0.0064[/tex]

And because there's 4 components, the chance that EXACTLY ONE works but the others don't is:

[tex]4 \cdot 0.0064 = 0.0256[/tex]

So we sum the probabilities:

[tex]P_{failure} = 0.0016 + 0.0256 = 0.0272\\P_{works} = 1 - P_{failure} = 0.9728[/tex]

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