Below is a distribution of race in the United States from 2014.
White= 60.5%
Black= 12.5%
Hispanic= 18.3%
Asian= 5.7%
Other= 3%
If we were to randomly choose 150 people for a survey, what is the probability that less than 70 of them would be white (round to 3 decimal places)?
Would this be unusual? If so, give some reasons why a particular sample might have less than 70 whites.
What is the probability that we would randomly choose a sample of 150 people and more than 22 of them were black (to 3 decimal places)?
What is the probability you would randomly select two Americans and they would both be white?
How many Asian people should we expect to have in a randomly selected group of 150 people?
In: Math
Delta airlines quotes a flight time of 2 hours, 5 minutes for its flight from Cincinnati to Tampa. Assume that the probability of a flight time within any one-minute interval is the same as the flight time within any other one-minute interval contained within the larger interval, 120 and 140 minutes.
*State the objective: What is the probability that the flight will be no more than 5 minutes late?
•Q1: What pdf best describes (models) the situation or assigns probabilities to outcomes of r.v.?
•Q2: Name and given values for parameters in the pdf.
•Q3: Define r. v.?
•Q4: Is r.v. discrete or continuous? (Make sure consistent with Q1)
•Q5: Write down the objective, question, or problem statement and then translate the English version into a statistics problem (using statistical and math language/formulas)
•Q6: Solve the objective.
In: Math
|
A random sample of 23 items is drawn from a population whose standard deviation is unknown. The sample mean is x⎯⎯x¯ = 820 and the sample standard deviation is s = 25. Use Excel to find your answers. |
| (a) |
Construct an interval estimate of μ with 99% confidence. (Round your answers to 3 decimal places.) |
| The 99% confidence interval is from to |
| (b) |
Construct an interval estimate of μ with 99% confidence, assuming that s = 50. (Round your answers to 3 decimal places.) |
| The 99% confidence interval is from to |
| (c) |
Construct an interval estimate of μ with 99% confidence, assuming that s = 100. (Round your answers to 3 decimal places.) |
| The 99% confidence interval is from to |
| (d) |
Describe how the confidence interval changes as s increases. |
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|
In: Math
Read the following statements and decide if they are true sometimes, always or never. Be sure to give a reason for each statement or use an example and the reason why it shows the statement is false. You can download this document in the module one section Fractions and attach it if you prefer.
In: Math
These questions come from MBA 5008
1. What is the difference between a point estimate and a confidence interval?
2. Is a point estimate alone is adequate?
3. Evaluating the effect of variability measurement (confidence interval) on the resulting estimates.
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Assume that a simple random sample has been selected from a normally distributed population and test the given claim. Identify the null and alternative hypotheses, test statistic, P-value, and state the final conclusion that addresses the original claim.
A coin mint has a specification that a particular coin has a mean weight of 2.5 g. A sample of 36 coins was collected. Those coins have a mean weight of 2.49502g and a standard deviation of 0.01562
Use a 0.05 significance level to test the claim that this sample is from a population with a mean weight equal to 2.5g
Do the coins appear to conform to the specifications of the coin mint?
test statistic z=
p=
In: Math
A researcher studied the relationship between the salary of a working woman with school-aged children and the number of children she had. The results are shown in the following frequency table:
Number of Children
|
Salary |
2 or fewer children |
more than 2 children |
|
high salary |
13 |
2 |
|
medium salary |
20 |
10 |
|
low salary |
30 |
25 |
If a working woman has more than 2 children, what is the probability she has a low or medium salary?
A. 0.79 B. 0.45 C. 0.35 D. 0.95
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Q 1.An online retailer, Mr Collins Ndhlovu, has two adverts posted in different parts of a well-known social networking website, Advertisement A and Advertisement B. An average of 2 ‘clicks’ are generated by Advertisement A during the period Monday 10.00 to 10.05am. There are on average 5 ‘clicks’ generated by Advertisement B during the same period. Calculate the probability that on a particular Monday between 10.00 and 10.05 am: i)Advertisement A generates at most 3 clicks. ii)Advertisement A generates at least 4 clicks. ii)Advertisement B generates no more than 4 clicks. iv)Advertisement A generates exactly 2 clicks and Advertisement B exactly 2 clicks. v)At least 3 clicks are generated in total by the two advertisements. (5marks)
In: Math
Explain the difference between a confidence interval and a prediction interval?
In: Math
The National Association of Home Builders provided data on the
cost of the two most popular home remodeling projects. Sample data
on cost in thousands of dollars for two types of remodeling
projects are as follows.
| Kitchen | Master Bedroom | Kitchen | Master Bedroom | |
| 27.0 | 18.0 | 23.0 | 17.8 | |
| 17.4 | 21.1 | 19.7 | 24.6 | |
| 22.8 | 26.4 | 16.9 | 22.0 | |
| 21.9 | 24.8 | 21.8 | ||
| 21.0 | 25.4 | 19.0 |
Using Kitchen as population 1 and Master Bedroom as population
2, develop a point estimate of the difference between the
population mean remodeling costs for the two types of projects (to
1 decimal).
$ thousand
Develop a 90% confidence interval for the difference between the
two population means (to 1 decimal). Use z-table.
( , )
In: Math
A recent survey reported that 39% of 18- to 29-year-olds in a certain country own tablets. Using the binomial distribution, complete parts (a) through (e) below.
a. What is the probability that in the next six 18- to 29-year-olds surveyed, four will own a tablet?
The probability is ? (Type an integer or a decimal. Round to four decimal places as needed.)
b. What is the probability that in the next six 18- to 29-year-olds surveyed, all six will own a tablet?
c. What is the probability that in the next six 18- to 29-year-olds surveyed, at least four will own a tablet?
d. What are the mean and standard deviation of the number of 18- to 29-year-olds who will own a tablet in a survey of six?
e. What assumption(s) do you need to make in (a) through (c)?
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The computer that controls a bank's automatic teller machine crashes a mean of 0.4 0.4 times per day. What is the probability that, in any seven-day week, the computer will crash less than 4 4 times? Round your answer to four decimal places.
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Describe the kind of data that are collected for an independent-measures t-test and the hypotheses that the test evaluates. The key to helping formulate your explanation would be to include the assumptions of this statistical model, the type of sample used in this model, and a statement about the null hypothesis.
In: Math
Calculate a geometric series
1.For v greater than 0 and less than 1, what is the Sum(v^i) for i = 1 to 100?
2.For v greater than 0 and less than 1, what is the Sum(v^i) for i = 1 to infinity?
3.Let v = 1/(1+r). State the answer to question 2 in terms of r.
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Question 1 contains the actual values for 12 periods (listed in order, 1-12). In Excel, create forecasts for periods 6-13 using each of the following methods: 5 period simple moving average; 4 period weighted moving average (0.63, 0.26, 0.08, 0.03); exponential smoothing (alpha = 0.23 and the forecast for period 5 = 53); linear regression with the equation based on all 12 periods; and quadratic regression with the equation based on all 12 periods. Round all numerical answers to two decimal places.
1. The actual values for 12 periods (shown in order) are:
(1)
45 (2)
52
(3)
48
(4)
59 (5)
55 (6)
54 (7)
64 (8)
59 (9)
72 (10)
66 (11)
67 (12)
78
Using a 5 period simple moving average, the forecast for period 13
will be:
2. Using
the 4 period weighted moving average, the forecast for period 13
will be:
3. With
exponential smoothing, the forecast for period 13 will be
4.
With linear regression, the forecast for period 13 will be:
5. With
quadratic regression, the forecast for period 13 will be:
6. Considering
only the forecasts for period 6-12, what is the lowest MAD value
for any of the methods?
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