Answer:
PQ = 6
Step-by-step explanation:
Using tangent-secant theorem,
(PQ)² = (PR)(PS)
(PQ)² = (4)(9)
(PQ)² = 36
Taking square root on both sides, we get
PQ = 6
Can someone please help? :)
Solution,
Diameter (d)=24 cm
Radius (r)=24/2 =12 cm
Circumference of circle= 2 pi r
=2*3.14*12
= 75.36 cm
Hope it helps
Good luck on your assignment
Answer:
[tex]c = 75.36cm[/tex]
Step-by-step explanation:
[tex]d = 2r \\ 24 = 2r \\ \frac{24}{2} = \frac{2r}{2} \\ r = 12cm[/tex]
[tex]circumference \\ = 2\pi \: r \\ = 2 \times 3.14 \times 12 \\ = 75.36cm[/tex]
hope this helps
brainliest appreciated
good luck! have a nice day!
Select all of the following that are quadratic equations.
Answer:
x^2 -2x = 4x+1
2x^2 +12x = 0
9x^2 +6x -3=0
Step-by-step explanation:
A quadratic equation has the highest power of x being squared
x^2 -2x = 4x+1
2x^2 +12x = 0
9x^2 +6x -3=0
These are all quadratic equations
A diameter of a particular circle has endpoints at A(-1, -2) and B(3,10). Which of the following is the
slope of the tangent drawn to this circle at point B?
A) -1/2
B) 4/5
C) -1/3
D) -4
Answer:
Option C) is correct
Step-by-step explanation:
Given: Endpoints of the diameter of the circle are A(-1, -2) and B(3,10)
To find: slope of the tangent drawn to the circle at point B
Solution:
Let [tex](x_1,y_1)=(-1,-2)\,,\,(x_2,y_2)=(3,10)[/tex]
Centre of the circle = [tex](\frac{x_1+x_2}{2},\frac{y_1+y_2}{2})=(\frac{-1+3}{2},\frac{-2+10}{2})=(1,4)[/tex]
Let [tex](h,k)=(1,4)[/tex]
Distance formula states that distance between points (a,b) and (c,d) is given by [tex]\sqrt{(c-a)^2+(d-b)^2}[/tex]
Radius of the circle = Distance between points [tex](-1,-2)[/tex] and [tex](1,4)[/tex] = [tex]\sqrt{(1+1)^2+(4+2)^2}=\sqrt{4+36}=\sqrt{40}[/tex] units
Let r = [tex]\sqrt{40}[/tex] units
Equation of a circle is given by [tex](x-h)^2+(y-k)^2=r^2[/tex]
[tex](x-1)^2+(y-4)^2=\left ( \sqrt{40} \right )^2\\(x-1)^2+(y-4)^2=40[/tex]
Differentiate with respect to x
[tex]2(x-1)+2(y-4)\frac{\mathrm{d} y}{\mathrm{d} x}=0\\\frac{\mathrm{d} y}{\mathrm{d} x}=\frac{1-x}{y-4}[/tex]
Put [tex](x,y)=(3,10)[/tex]
[tex]\frac{\mathrm{d} y}{\mathrm{d} x}=\frac{1-3}{10-4}=\frac{-2}{6}=\frac{-1}{3}[/tex]
So,
slope of the tangent drawn to this circle at point B = [tex]\frac{-1}{3}[/tex]
PLEASE HELP ITS URGENT! 20 POINTS WORTH (basic inverse function question)
Answer:I believe the answer is -1,-4 lies on the graph
Step-by-step explanation:
A random sample of 1285 residents from rural and urban areas were surveyed about their opinion about using daylight savings time. Below is the gathered data. Assuming there’s no relationship between residential area and opinion on daylight savings time, how many people who live in a rural area would you expect to be in favor of continuing to use daylight savings time? Please round up to a whole number.
Stop using Daylight Savings Time Continue using Daylight Savings Time Total
Rural 341 281 622
Urban 353 310 663
Total 694 591 1285
Pearson's Chi-square test
X-squared 0.32 df= 1 p-value ?
Answer:
The expected number of people that lives in rural areas and is in favor of continuing using daylight savings time is 287.
Step-by-step explanation:
Hello!
There were 1285 residents from rural and urban areas surveyed about their opinion about using savings time. There are two variables of interest:
X₁: Area where the resident lives, categorized: "Rural area", "Urban area".
X₂: Opinion about using daylight savings time, categorized: "Stop", "Continue".
To know how many people who live in a rural area would you expect to be in favor of continuing to use daylight savings time, you have to calculate the expected frequency for that cell (See table in attachment)
The formula to calculate the expected frequencies is:
[tex]E_{ij}= \frac{O_{i.}*O_{.j}}{n}[/tex]
i: categories in rows i=1, 2
j: categories in columns j= 1, 2
Oi.: total observations for the i-row
O.j: total observations for the j-row
The category "rural" is in the first row, so its marginal is symbolized O₁.
The category "Continue" is in the second column, so its marginal is symbolized O.₂
The expected frequency for the people that live n rural areas and is in favor of continuing using daylight savings time is:
[tex]E_{12}= \frac{O_{1.}*O.2}{n}= \frac{622*591}{1285} = 286.07= 287[/tex]
I hope this helps!
Find the value of 5(x - y)
Answer:
= 5x-5y
Step-by-step explanation:
Multiply 5to x and y
Answer:
5x-5y
Step-by-step explanation:
multiply both the terms x and y by 5.
The earth moves at about 98,000 feet per second as it resolves around the Sun. How fast is that in miles per hour?> (recall that 1 mile is 5,280.00 feet.)
Answer:
[tex]\frac{98000 ft}{1 second}\times \frac{? second}{1 hour}\times \frac{1 mile}{5280 ft}[/tex]
Step-by-step explanation:
If you cancel out the same unit, one from numerator and one from denominator, you will get mile/ hour as asked. The leftover is doing your math.
You finish your work!!
I don't care about the evaluation. I do care if you can work by yourself and understand the work
Some accounting firms give the client an option to pay a fee when the tax return is completed that guarantees tax advices and support from the accountant if the client were audited. A large accounting firm is trying to determine what fee to charge for nextyear's returns. In previous years, the actual mean cost to the firm for attending a client audit session was $690. To determine if this cost has changed, the firm randomly samples 35 client audit fees. The sample mean audit cost was $700 with a standard deviation of $65.
Required:
a. Develop a 90% confidence interval estimate for the mean audit cost.
b. Based on your confidence interval, what do you think of the claim that the mean cost has changed?
1. The interval does not contain the historical data mean $690, which supports claim the mean cost has changed.
2. The interval contains historical data mean $690, which supports the claim the mean cost has changed.
3. The interval does not contains historical data mean $690, which does not support the claim it has changed.
4. The interval contains historical data mean $690, which does not support the claim the mean cost has changed.
Answer:
a) $700+/-$18.07
Therefore,the 90% confidence interval (a,b)
= ($681.93, $718.07)
b) 4. The interval contains historical data mean $690, which does not support the claim the mean cost has changed.
Step-by-step explanation:
Confidence interval can be defined as a range of values so defined that there is a specified probability that the value of a parameter lies within it.
The confidence interval of a statistical data can be written as.
x+/-zr/√n
Given that;
Mean x = $700
Standard deviation r = $65
Number of samples n = 35
Confidence interval = 90%
z(at 90% confidence) = 1.645
a. Develop a 90% confidence interval estimate for the mean audit cost.
Substituting the values we have;
$700+/-1.645($65/√35)
$700+/-1.645($10.98700531147)
$700+/-$18.07362373736
$700+/-$18.07
Therefore,the 90% confidence interval (a,b) = ($681.93, $718.07)
b) Since, $690 is contained between the 90% confidence interval of ($681.93, $718.07). It implies that the mean cost has not changed.
4. The interval contains historical data mean $690, which does not support the claim the mean cost has changed.
A truck was purchased for $120,000 and it was estimated to have a $24,000 salvage
value at the end of its useful life. Monthly depreciation expense of $2,000 was recorded
using the straight-line method. The annual depreciation rate is
Answer:
25
Step-by-step explanation:
The expression (2x + 1)4 is expanded and simplified. Which monomial listed below is a term in the result? 8x3 12x3 32x3 48x3
Answer:
32x^3
Step-by-step explanation:
[tex](2x+1)^4=(2x)^4+4(2x)^3(1)+6(2x)^2(1)^2+4(2x)(1)^3+(1)^4\\\\=16x^4 +\boxed{32x^3} +24x^2+8x+1[/tex]
_____
Comment on the question
It is helpful if you designate exponents with a caret (^). We expect the expanded form of (2x+1)4 to be 8x+4. (2x+1)^4 is entirely different. Similarly, 8x3 = 24x, whereas 8x^3 is something else.
32x^3
It is helpful if you designate exponents with a caret (^). We expect the expanded form of (2x+1)4 to be 8x+4. (2x+1)^4 is entirely different. Similarly, 8x3 = 24x, is the answer to the question
which equation represents a circle with a radius of 8 centered at (-3,4)
Answer:
(x+3)^2 + (y-4)^2 = 64
Step-by-step explanation:
We can write the equation of a circle as
(x-h)^2 + (y-k)^2 = r^2 where ( h-k) is the center and r is the radius
(x--3)^2 + (y-4)^2 = 8^2
(x+3)^2 + (y-4)^2 = 64
Write a differential equation that is a mathematical model of the situation described. The time rate of change in the temperature T of coffee is proportional to the difference between the fixed temperature M of the air at time t and the temperature of the coffee at time t. The differential​ equation, with proportionality constant​ k, is nothing.
how to read pathater in himdi
If 75 g of active ingredient powder is mixed with 400 mL NS solution, what is the final concentration? Round to the nearest hundredths (w/v).
75g/400ml: Simplify per unit
÷ by bottom.
0.1875g/ml nearest hundredth
0.19g/ml
The linear equation graphed above gives the height in feet above the ground of Shelly t seconds after she opened her parachute when jumping from an airplane. According to the graph, how many seconds after opening her parachute will Shelly be 2,000 feet above the ground?
Answer:
[tex]\large \boxed{\text{60 s}}[/tex]
Step-by-step explanation:
Assume your graph looks like the one below.
1. Calculate the equation of the straight line
The slope-intercept equation for a straight line is
y = mx + b
where m is the slope of the line and b is the y-intercept.
The line passes through the points (0,2600) and (30, 2300)
(a) Calculate the slope of the line
[tex]\begin{array}{rcl}m & = & \dfrac{y_{2} - y_{1}}{x_{2} - x_{1}}\\\\ & = & \dfrac{2300 - 2600}{30 - 0}\\\\& = & \dfrac{-300}{30}\\\\& = & \text{-10 ft/s}\\\\\end{array}[/tex]
(b) Locate the y-intercept
The y-intercept is at 2600 ft
(c) Write the equation for the line
h = -10t + 2600
(d) Calculate the time to 2000 ft
[tex]\begin{array}{rcl}h & = & -10t + 2600\\2000 & = & -10t + 2600\\-600 & = & -10t\\t & = & \dfrac{-600}{-10}\\\\& = & \text{60 s}\\\end{array}\\[/tex]
Shelley will be at 2000 ft 60 s after opening the parachute.
Let the given line pass through the point that is [tex]\bold{(0,2600)\ \ and\ \ (20, 2400)}[/tex]
[tex]\therefore[/tex]
[tex]\to \bold{\frac{H-2400}{t-20}} \bold{= \frac{2600-2400}{0-20}}\\\\[/tex]
[tex]\bold{=\frac{200}{-20} }\\\\ \bold{= -\frac{200}{20}}\\\\ \bold{= - 10}\\\\[/tex]
[tex]\to \bold{H-2400=-10t+200}\\\\\to \bold{H+10t=2400+200}\\\\\to \bold{H+10t=2600}\\\\\to \bold{H=2600-10t}\\\\[/tex]
Let
time (t) in second
Height (h) in feet
for [tex]\bold{\ H=2000\ feet\\}[/tex]
[tex]\to \bold{2000=2600-10t}\\\\\to \bold{10t = 2600- 2000}\\\\\to \bold{10t = 600}\\\\\to \bold{t=\frac{600}{10}}\\\\\to \bold{t= 60\ second}\\\\[/tex]
Learn more:
brainly.com/question/3012638
Round 954 to the nearest hundred.
Answer:
1000
Step-by-step explanation:
5 or more add one more
4 or less let it rest
so it becomes 1000
Wind Mountain is an archaeological study area located in southwestern New Mexico. Potsherds are broken pieces of prehistoric Native American clay vessels. One type of painted ceramic vessel is called Mimbres classic black-on-white. At three different sites the number of such sherds was counted in local dwelling excavations.
Site I Site II Site III
51 47 33
45 19 57
32 9 62
19 18 28
25 28
57 22
35
Shall we reject or not reject the claim that there is no difference in population mean Mimbres classic black-on-white sherd counts for the three sites? Test given b807b7c2-a348-4cb7-8322-f58461059cce.GIF.
What is the level of significance?
a. 90%
b. 1%
c. 5%
d. 99%
e. 95%
Answer:
Step-by-step explanation:
Hello!
This is an example of an ANOVA hypothesis test, where you'll compare the population means of the number of broken Mimbres in three different excavation sites.
The variable of interest is
Y: Number of broken pieces of prehistoric Native American clay vessels, called Mimbres in an excavation site.
Factor: Site
Treatments: 1, 2, 3
You are asked to identify the level of significance of the test. This value is the probability of committing Type I error, that is, when you fail to reject a false null hypothesis and is always represented with the Greek letter alpha "α"
This level is determined by the researcher when he is designing the experiment and statistical analysis. Normally you'd want this level to be as small as possible to be sure you didn't commit any mistake when deciding over the hypotheses.
The mos common values are 0.01, 0.05 or 0.1 and it can also be expressed as percentages 1%, 5% or 10%. Having a probability of making a mistake greater than 10% is too high so normally you would not encounter significance levels greater than 10%
With this in mind options b. 1% and c. 5% are valid values for α.
Have a nice day!
Next time check that all the information is copied!
Mary crocheted a rectangular blanket whose diagonal measures approximately 7.21 feet. What are the most likely length and width measurements of the blanket ? Select the two correct answers.
Answer:
If both sides are integers, one side will be 4 feet and the other will be 6 feet. The other solution is the symmetrical solution (4 feet instead of 6 feet, and 6 feet instead of 4 feet).
Step-by-step explanation:
We have a rectangular blanket, that has a diagonal that measures h=7.21 feet.
The two sides of the rectangle a and b can be related to the diagonal h by the Pithagorean theorem:
[tex]a^2+b^2=h^2[/tex]
Then, we can express one side in function of the other as:
[tex]a^2+b^2=h^2\\\\a^2=h^2-b^2\\\\a=\sqrt{h^2-b^2}=\sqrt{7.21-b^2}=\sqrt{52-b^2}[/tex]
Then, if we define b, we get the value of a that satisfies the equation.
A graph of values of a and b is attached.
If both side a and b are integers, we can see in the graph that are only two solutions: (b=4, a=6) and (a=4, b=6).
How many school buses will be needed to take the children of Anderson school on a field trip ? Each bus can carry 60 people. 390 children and 30 adults are going on the trip
Answer:
7 school buses will be needed to take the children of Anderson school on a field trip
Step-by-step explanation:
number of children = 390
We are told that each bus carries 60 people
Therefore
60 people = 1 bus
1 person = (1 ÷ 60)
∴ 390 people = [tex]\frac{1}{60}[/tex] × [tex]\frac{390}{1}[/tex] = [tex]\frac{390}{60}[/tex] = 6.5 (approx. 7 buses)
Therefore, 7 school buses will be needed to take the children of Anderson school on a field trip, but the seventh bus will be half-filled with children.
A math class is having a discussion on how to determine if the expressions 4 x minus x + 5 and 8 minus 3 x minus 3 are equivalent using substitution. The class has suggested four different methods. Which describes the correct method?
Answer:
Both expressions should be evaluated with one value. If the final values of the expressions are the same, then the two expressions must be equivalent.
Step-by-step explanation:
Answer:
The answer is:
B. Both expression should be evaluated with one value if the final values of the expressions are the same then the two expressions must be equivalent
Use each number only once. Add, subtract multiply, or divide to get an awnser of 3. Use all numbers, show your work
8,6,5,9,1
Answer:
these are my answers:
8-5=3
2÷6=3
5-2=3
2+1=3
3÷9=3
Answer:
9 +6 +1 -8 -5 = 3
Step-by-step explanation:
There are numerous possibilities. Among them are ...
9 +6 +1 -8 -5 = 3
(9-5)·1·6/8 = 3
(9·8)/(6·(5-1)) = 3
Sugar canes have lengths X that are normally distributed with mean 365.45 cm and standard deviation 4.9 cm what is the probability of the length of a randomly selected Cane being between 360 and 370 cm
Answer:
The probability of the length of a randomly selected Cane being between 360 and 370 cm P(360 ≤X≤370) = 0.6851
Step-by-step explanation:
step(i):-
Let 'X' be the random Normal variable
mean of the Population = 365.45
Standard deviation of the population = 4.9 cm
Let X₁ = 360
[tex]Z= \frac{x-mean}{S.D}= \frac{360-365.45}{4.9}[/tex]
Z₁ = -1.112
Let X₂ = 370
[tex]Z= \frac{x-mean}{S.D}= \frac{370-365.45}{4.9}[/tex]
Z₂ = 0.911
Step(ii):-
The probability of the length of a randomly selected Cane being between 360 and 370 cm
P(x₁≤x≤x₂) = P(z₁≤Z≤z₂)
P(360 ≤X≤370) = P(-1.11≤Z≤0.911)
= P(Z≤0.911)-P(Z≤-1.11)
= 0.5 +A(0.911) - (0.5-A(1.11)
= 0.5 +A(0.911) - 0.5+A(1.11)
= A(0.911) + A(1.11)
= 0.3186 + 0.3665
= 0.6851
The probability of the length of a randomly selected Cane being between 360 and 370 cm P(360 ≤X≤370) = 0.6851
in a poll 267 students voted. nominee c received 2/3 of the votes. how many votes did nominee c receive?
Answer:
89
Step-by-step explanation:
2/3 times 267 is 178 after that you have to sub 178 from 267
Arguably, the top 5 race horses in U.S. history are Secretariat (S), Man O'War (M), Citation (C), War Admiral (W), and Seabiscuit (B).
Required:
a. Use this information to determine the number of possible samples (without replacement) of size 22 that can be obtained from the population of size 55.
b. If a simple random sampling procedure is to be employed, the chances that any particular sample will be the one selected are:________
Answer:
a) 10
b) 0.1 = 10%
Step-by-step explanation:
The combinations formula is used to solve this question, since the horses are chosen without replacement.
Combinations formula:
[tex]C_{n,x}[/tex] is the number of different combinations of x objects from a set of n elements, given by the following formula.
[tex]C_{n,x} = \frac{n!}{x!(n-x)!}[/tex]
a. Use this information to determine the number of possible samples (without replacement) of size 2 that can be obtained from the population of size 5.
Combinations of 2 objects from a set of 5. So
[tex]C_{5,2} = \frac{5!}{2!(5-2)!} = 10[/tex]
b. If a simple random sampling procedure is to be employed, the chances that any particular sample will be the one selected are:________
In this procedure, the samples are all equally as likely to be chosen.
So
1/10 = 0.1 = 10%
What two methods are the best choices to factor this expression?
18x2-8
-Factor by grouping.
-Factor out the GCF.
-Use the difference of squares rule.
-Use the perfect square trinomial rule.
Answer:
- Factor by grouping. - Factor out the GCF.Step-by-step explanation:
Given the expression 18x²-8, the best method to factor this expression are Factor by grouping and by factoring out the greatest common factor.
Step 1: Factor by grouping
Factor by grouping is done by creating a smaller groups from each term in the expression as shown;
18x² = (2*3*3* x²)
8 = 2*2*2
18x²-8 = (2*3*3* x²) - (2*2*2)
Step 2: Then we will factor out the greatest common factor (GCF) in the expression. GCF is the value that is common to both terms of the expression. The only common term in this case is 2.
Answer:
Factor out the GCF, and Use the difference of squares rule.
Step-by-step explanation:
The terms in the expression have a common factor of 2, so the first step is to factor out the GCF:
2(9x2 − 4).
Then, factor the remaining expression using the difference of squares rule.
Find the inequality represented by the graph
Answer:
There is no graph to find an inequality on...
Step-by-step explanation:
need!!!!!!!!!!!help!!!!!!Asap!!!!!!
Answer:
225 feet below sea level (or -225 feet)
Step-by-step explanation:
My apologies in advance if this does not format the way its supposed to. The way I did it includes arrows and may work best on a computer.
Problem: A submarine that is 245 feet below sea level descends 83 feet and then ascends 103 feet. Which represents the location of the submarine compared to sea level.
Math: Ok, so we know that whenever something descends, that means it is going down, so let's use a negative sign. These means when something ascends, it goes up. Let's use a positive sign here. Also, note the fact that we start 245 feet below sea level. This means we should start at -245.
Now, using the data we have, let's create a math problem.
A submarine that is 245 feet below sea level descends 83 feet and then ascends 103 feet. Which represents the location of the submarine compared to sea level.
-245 <---- beginning level
-83 <---- the submarine descends
+103 <---- the submarine ascends
_______
?
So grab a calculator to do this part, or do it on your own. Once you finish, plug in the answer.
-245 -245
-83 -83
+103 ---------------> +103
______ ________
? -225 feet
So as you can see, the final answer would be -225 feet or 225 feet below sea level.
Hope this helped! Have a great day!
What’s the correct answer for this? Select all the apply
Answer:
B and C
Step-by-step explanation:
AP = BP
OC = OD
ANSWER A water tower in New York City has the shape of a cylinder with a cone on top. The cylinder has a diameter of 12 feet and a height of 15 feet. The roof has an inclination angle of 25o . There are 7.48 gallons in a cubic foot. If residents of an apartment building are using the water from the tower at an average rate of 56 gallons per minute, determine how long, to the nearest minute, it will take to drain the entire tower.
Answer:
241 minutes
Step-by-step explanation:
Given:
Height of cylinder, h = 15 ft
Radius, r = [tex] \frac{d}{2} = \frac{12}{2} = 6 [/tex] (both cylinder and cone have same radius)
Let's find the height of cone, since angle of inclination = 25°C.
[tex] tan25 = \frac{h}{r} [/tex]
[tex] h = r tan25 [/tex]
[tex] h = 6 tan25 = 2.8 [/tex]
Height of cone = 2.8 ft
Let's find colume of tower.
Volume = Volume of cone + volume of cylinder.
Formula for volume of cone = ⅓πr²h
Volume of cylinder = πr²h
Therefore,
V = ⅓πr²h + πr²h
V = ⅓π*6²*2.8 + π*6²*15
V = 105.558 + 1696.46
V = 1802.02 ft³
Since volume is 1802.02 ft³, and there are 7.48 gallons in a cubic ft, the total gallon =
1802.02 * 7.48 = 13479.11 gallons
Water is used at an average rate of 56 gallons per minute.
Amount if time to drain the water:
Total gallons / average rate
[tex] = \frac{13479.11}{56} = 240.698 [/tex]
≈ 241 minutes
tg105°-cotg105° = ?
Please help fast!!! Please
Using only the trig ratios of 45 and 60 degrees, we use angle-sum to compute [tex]\tan 105^\circ=\tan(60^\circ+45^\circ)=\frac{\tan 60^\circ+\tan 45^\circ}{1-\tan 60^\circ\tan 45^\circ}=\frac{\sqrt{3}+1}{1-\sqrt{3}}=-2-\sqrt{3},[/tex] so [tex]\cot 105^\circ=\frac{1}{\tan 105^\circ}=-2+\sqrt{3}[/tex] and [tex]\tan 105^\circ-\cot105^\circ=\boxed{-2\sqrt{3}}.[/tex]
A travel magazine conducts an annual survey where readers rate their favorite cruise ship. Ships are rated on a 10 point scale, with higher values indicating better service. A sample of 20 ships that carry fewer than 500 passengers resulted in a average rating of 6.93 with standard deviation 0.31. A sample of 55 ships that carry more than 500 passengers resulted in an average rating of 7.07 with standard deviation 0.6. statcrunch. Assume that the population standard deviation is 4.58 for ships that carry fewer than 500 passengers and 3.95 for ships that carry 500 or more passengers.
Round your all answers to two decimal places.
a. What is the point estimate of the difference between the population mean rating for ships that carry fewer than 500 passengers and the population mean rating for ships that carry 500 or more passengers?
b. At 95% confidence, what is the margin of error?
c. What is a 95% confidence interval estimate of the difference between the population mean ratings for the two sizes of ships?
Answer:
a) The point estimate of the difference between the populations is Md=-0.14.
b) The margin of error at 95% confidence is 0.212.
c) The 95% confidence interval for the difference between means is (-0.352, 0.072).
Step-by-step explanation:
We have to calculate a 95% confidence interval for the difference between means.
The sample 1 (ships under 500 passengers), of size n1=20 has a mean of 6.93 and a standard deviation of 0.31.
The sample 2 (ships over 500 passengers), of size n2=55 has a mean of 7.07 and a standard deviation of 0.6.
The difference between sample means is Md=-0.14.
[tex]M_d=M_1-M_2=6.93-7.07=-0.14[/tex]
The estimated standard error of the difference between means is computed using the formula:
[tex]s_{M_d}=\sqrt{\dfrac{\sigma_1^2}{n_1}+\dfrac{\sigma_2^2}{n_2}}=\sqrt{\dfrac{0.31^2}{20}+\dfrac{0.6^2}{55}}\\\\\\s_{M_d}=\sqrt{0.005+0.007}=\sqrt{0.011}=0.11[/tex]
The critical t-value for a 95% confidence interval is t=1.993.
The margin of error (MOE) can be calculated as:
[tex]MOE=t\cdot s_{M_d}=1.993 \cdot 0.11=0.212[/tex]
Then, the lower and upper bounds of the confidence interval are:
[tex]LL=M_d-t \cdot s_{M_d} = -0.14-0.212=-0.352\\\\UL=M_d+t \cdot s_{M_d} = -0.14+0.212=0.072[/tex]
The 95% confidence interval for the difference between means is (-0.352, 0.072).