Researchers investigated whether providing a fancy, foil-wrapped piece of chocolate with the dinner bill would lead to higher tips than not providing such a treat. Sixty-four dinner parties at a restaurant in Ithaca, NY were randomly assigned to receive such a piece of chocolate or not with their dinner bill. Of the 32 parties who received the chocolate, the average tip (as a percentage of the bill) was 17.84%, with a standard deviation of 3.06%. Of the 32 parties who did not receive the chocolate, the average tip (as a percentage of the bill) was 15.06%, with a standard deviation of 1.89%. Determine a 96% confidence interval for the size of the difference in average tips between the two groups
Answer:
The 96% confidence interval for the size of the difference in average tips between the two groups is (1.47%, 4.09%).
Step-by-step explanation:
Before building the confidence interval, we need to understand the central limit theorem and subtraction of normal variables.
Central Limit Theorem
The Central Limit Theorem estabilishes that, for a normally distributed random variable X, with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean [tex]\mu[/tex] and standard deviation [tex]s = \frac{\sigma}{\sqrt{n}}[/tex].
For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.
Subtraction of normal variables:
When we subtract normal variables, the mean is the subtraction of the means while the standard deciation is the square root of the sum of the variances.
Of the 32 parties who received the chocolate, the average tip (as a percentage of the bill) was 17.84%, with a standard deviation of 3.06%.
This means that:
[tex]\mu_{C} = 17.84, s_{C} = \frac{3.06}{\sqrt{32}} = 0.541[/tex]
Of the 32 parties who did not receive the chocolate, the average tip (as a percentage of the bill) was 15.06%, with a standard deviation of 1.89%.
This means that:
[tex]\mu_{NC} = 15.06, s_{NC} = \frac{1.89}{\sqrt{32}} = 0.3341[/tex]
Difference in average tips
The distribution has mean:
[tex]\mu = \mu_{C} - \mu_{NC} = 17.84 - 15.06 = 2.78[/tex]
Standard deviation:
[tex]s = \sqrt{s_{C}^2 + s_{NC}^2} = \sqrt{0.541^2 + 0.3341^2} = 0.6358[/tex]
96% confidence interval
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 - 0.96}{2} = 0.02[/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 - 0.02 = 0.98[/tex], so Z = 2.054.
Now, find the margin of error M as such
[tex]M = zs[/tex]
[tex]M = 2.054*0.6358 = 1.31[/tex]
The lower end of the interval is the sample mean subtracted by M. So it is 2.78% - 1.31% = 1.47%
The upper end of the interval is the sample mean added to M. So it is 2.78% + 1.31% = 4.09%
The 96% confidence interval for the size of the difference in average tips between the two groups is (1.47%, 4.09%).
Herons formula triangle is
Answer:
Heron's formula (sometimes called Hero's formula), named after Hero of Alexandria, gives the area of a triangle when the length of all three sides are known. Unlike other triangle area formulae, there is no need to calculate angles or other distances in the triangle first.
The table represents equivalent ratios of x to y. Find the missing numbers in the table.
Х
y
15
20
16
25
o
30
24
Help me please its due in 20 minutes!!!!
Sean and Hope are going bowling. For each person, a game costs $4.25. Shoe rentals are $3.00. Sean gives the clerk $20 for their admission and shoe rental. How much change should he receive? *
1 point
$12.75
$5.50
$9.75
$14.50
PLZ HELPPP ME NEED IT BY TODAYYYYYYYYYY!!!!!!!!!!!!!
Answer:
The answer is 5.50.
Step-by-step explanation:
First, you do 4.25+3.00=7.25
Second, 20-7.25=12.75
but read the beggining again it says sean AND hope so repeat the step again.
First, you do 4.25+3.00=7.25
Second, 20-14.50=5.50
A rectangular lawn measuring 24 feet by 16 feet is surrounded by a flower bed of uniform width. The combined area of the lawn and the flower bed is 660 square feet. What is the width of the flower bed?
Answer:
6 feet
Step-by-step explanation:
(24+x)(16+x)=660
384+24x+16x+x²=660
x²+40x-276=0
x`= 6
x```= -46......no serve
Answer......is 6 feet
The width of the flower bed is 6 feet.
What is the area of a rectangle?The area of any shape is the number of unit squares that fit inside it. Here "unit" refers to 1, and a unit square is a square with sides of 1 unit.So the area of a rectangle is the number of unit squares within the bounds of the rectangle.Alternatively, the space occupied around this shape is called the area of the rectangle.The area occupied by the bounding rectangle is called the rectangular area.Area can be defined as the amount of space covered by a plane of a particular shape.It is measured in "number" of square units (square centimeters, square inches, square feet, etc.).The area of a rectangle is the number of unit squares that fit in the rectangle.Examples of rectangles are flat surfaces such as laptop monitors, chalkboards, and canvases.6 feet is the width of the flower bed.
(24+x)(16+x)=660
384+24x+16x+x²=660
x²+40x-276=0
x`= 6
x```= -46 which cannot be the case, therefore 6 feet is the width of the flower bed.
To learn more about area, refer
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#SPJ2
I WILL GUVE BRAINERLEST AND A LIKE
Jack needs to replace some flooring in
his house.
Answer:
B
Step-by-step explanation:
i think
A farmer sells 6.5 kilograms of apples and pears at the farmer's market.
3
4
of this weight is apples, and the rest is pears. How many kilograms of pears did she sell at the farmer's market?
Answer:
1.625 kg
Step-by-step explanation:
9 cm
4 cm
1
14 cm
5 cm
Answer:
this is D
Step-by-step explanation:
I NEED HELP LIKE ASAP PLS!!!!
Answer:
formula 3 only
Step-by-step explanation:
formula for the are of a circle is [tex]A=\pi r^{2}[/tex]
the other 2 formulas are the ones for circumference
Hows your day i just want to know: Who are your top 3 favorite rappers? And give me your or one of your favorite songs by each one?
Answer:
um mm
Brent fayiyz
all his songs
and ummm
Help me quickly!!! I'll try to give Brainlyest
Answer:
number 12 is A for sure
How many quarters are there in 4
22?
2
134
Answer.
Determine the average percent of change from 1960–2000
1960 1970 1980 1990 2000
$0.25 $0.36 $1.19 $1.35 $1.26
show your work
Answer:
1970 +46%
1980 +232%
1990 +14%
2000 -8%
Step-by-step explanation:
An event that is guaranteed to happen has a probability of exactly
Answer:
100%
Step-by-step explanation:
It is confirmed to happen, or [tex]\frac{100}{100}[/tex]
Answer:
An event that is guaranteed to happen has a probability of exactly 1
5x +60/x -15x +15/x-20
Answer:
5x-60=x - solution,..........
Answer:
Answer:
5x +60/x -15x +15/x-20
60/x+15/x-15x+5x-20
75/x-10x-20
is your answer
combined liked terms by adding and subtracting.
How much money is 5 dollars, 10 dimes, and 10 pennies?
Answer:
6 dollars and 10 cents
Step-by-step explanation:
I'm sorry this isn't the answer, but I just want you to know that you are incredible and that I love you for you! You are special to everyone you meet, and should not change who you are. I know your life may be tough, but you are strong and can get through it!
The area of a SQUARE is 22 ft2. Which of the following is the closest to
the length of each SIDE of the square?
Answer:
4.7ft
Step-by-step explanation:
Hello, the answer would be 4.7ft because 4.7^2 is closest to 22ft^2 with it being 22.09ft^2.
HELP ME PLEASE!!! No links
Answer:
H 60
Step-by-step explanation:
You would need to find out what you would multiply times 0.5 to get 30. Then to get that answer just divide 30 by 0.5. which is 60
Please help me.. I don't undersand this
Answer:
45 degrees.
Step-by-step explanation:
When two angles are next to each other along a straight line, their sum = 180 degrees.
180 - 135 = 45
Answer:
I know i may be unwanted here but I just want you to know that you are incredible and that I love you for you! You are special to everyone you meet, and should not change who you are. I know your life may be tough, but you are strong and can get through it!
Step-by-step explanation:
Find the value of x in the triangle shown below x 42 106
Answer:
Step-by-step explanation:
where is the picture?
Answer:
you need a picture lol
Step-by-step explanation:
Free brainlest! Just answer this....... WHAT IS BETTER PS4 OR Xbox if you get it right you can have it!
Answer:
Depends
Step-by-step explanation:
PS4 has a better gaming system and better games (Spiderman example)
But Xbox has the better controller. I think Xbox is better I prefer it but it doesn't really matter.
Find the mean absolute deviation of the set of data. Round your answer to two
decimal places.
3, 1, 5, 4, 8,6
Answer:
4.5 is the mean/average
Step-by-step explanation:
3+1+5+4+8+6=27
27 divided by 6 = 4.5
how can you use the multiplicative inverse to solve division problems?
(best answer gets brainliest)
Answer:
Hello, the multiplicative inverse is just another name for reciprocal. You can use this type of method when dividing fractions like:
1/2/3/5
You use the method known as kfc, keep, flip, change like this:
1/2 x 5/3
Notice how 1/2 is kept the same, the division sign is now a multiplying sign, and 3/5 is flipped.
And then you just answer it from there and you get 5/6
Step-by-step explanation:
I hope this helped you!
On the number line, plot and label all numbers with an absolute value of 32. Where did you place the points?
Answer:
on 32 and -32
Step-by-step explanation:
Find the circumference and area of a circle with diameter of 18 inches. Use 3.14 for pi. Write your answer as decimals rounded to the nearest hundredth.
a. C = 56.52 in, A = 1017.36 in2
b. C = 56.52 in, A = 254.34 in2
c. C = 113.04 in, A = 254.34 in2
d. C = 113.04 in, A = 1017.36 in2
e. None of the above are correct.
Answer: b
Step-by-step explanation:
Radius = 9 inches, Pi= 3.14
Circumference = 2 x pi x radius = 2 x (3.14) x 9 = 56.52
Area = pi x radius x radius = (3.14) x 9 x 9 = 254.34
Answer:
Answer attached
Step-by-step explanation:
What is the length from Alaska to Chicago times 5 divided by 3?
Answer:
14302 miles
Step-by-step explanation:
from alaska to chicago it is 2861 mi.
2861 times 5
that divdied by three is 14302
what’s the domain of this relation?
Answer:
there is nothing here but thanks for the points
Step-by-step explanation:
Have a great rest of your day/night!
Unit 11: Volume & Surface Area Homework 3: Area of Composite Figures find the area of each figure. found to the nearest hundredth where necessary.
Answer: 7.5
Step-by-step explanation:
A1=1/2pir^2 A2=1/2pir^2
1/2(121pi) 1/2(16pi)
5.5 2
The area of a composite shape is the sum of the areas of its individual shapes
The area of the composite shape is 215.20 square feet.
From the figures, we have the following shapes
A semicircle with a diameter of 22 ftA semicircle with a diameter of 8 ft (i.e. 30ft - 22ft)The area (A) of a semicircle is:
[tex]\mathbf{A = \frac{\pi d^2}{8}}[/tex]
So, the area of the composite shape is:
[tex]\mathbf{A = \frac{\pi (d_1^2 + d_2^2)}{8}}[/tex]
This gives
[tex]\mathbf{A = \frac{\pi (22^2 + 8^2)}{8}}[/tex]
[tex]\mathbf{A = \frac{\pi (548)}{8}}[/tex]
[tex]\mathbf{A = 68.5\pi}[/tex]
[tex]\mathbf{A = 215.20}[/tex]
Hence, the area of the composite shape is 215.20 square feet.
Read more about areas at:
https://brainly.com/question/16741417
A store stocked 150 cans of popcorn for a weekend sale. That Weekend, 99 of the cans sold. What percentage of cans of popcorn stocked were unsold that weekend?
Answer:
34%
Step-by-step explanation:
99/150 = 0.66
1.00 - 0.66 = 0.34
34%
Answer:There is 48% of cans