统计学的基本概念代写 统计学代写 统计考试代考 统计代做

Practice Midterm

统计学的基本概念代写 Part I. Points and Number within sections are approximate and may change. Short Answers –2 points each (5) 1.Will we get nominal or ordinal data

Part I.  Points and Number within sections are approximate and may change.

Short Answers –2 points each (5)

1.Will we get nominal or ordinal data if:  

• Professors rate their midterms as very difficult, difficult, easy or very easy.

• The codes for the boroughs are coded 1=Brooklyn, 2= Queens 3= Bronx 4 = Manhattan 

2.A survey indicates that the vast majority of college students own more than 1 computer.

What information would you want to know before you accepted the results of this survey, and why?

3.Answer true or false to each statement. Explain your answer.

• Two normal distributions that have the same mean are centered at the same place regardless of the relationships between their standard deviations.  

• Two normal distributions that have the same standard deviations have the same spread, regardless of the relationship between their means.

4.Suppose that you are given complete information about the travel expenses which the administrators of a school system applied to their expense accounts during 2019.  Give one illustration each of a situation where these data would be looked upon as,

a) population   b) a sample  

Part II. 统计学的基本概念代写

Calculate and Interpret – 3-4 points each (4-5 questions on midterm)

1.Calculate the requested statistics for the given sample data.

Sample Data: 68, 84, 93, 68, 70

(a) mean:

(b) median:

(c)  mode:

(d) range:

(e) sample variance:

(f)  sample standard deviation: 

2.Use a table of areas to find the specified area under the standard normal curve.

3.The area that lies between -1.10 and -0.36

4.A quantitative dataset has mean 15 and standard deviation 2.

Approximately what percentage of observations lie between 13 and 17?

What is the probability you would draw one observation from this area?. 统计学的基本概念代写

5.A variable is normally distributed with mean 10 and standard deviation of 3.  Find the percentage of all possible values of all variables that-

• lie between 6 and 7
• are at least 10
• are at most 17

6.Which of the following statements concerning areas under the standard normal curve is/are true?

a. If a z-score is negative, the area to its right is greater than 0.5

b. If the area to the right of a z-score is less than 0.5, the z-score is negative.

c. If a z-score is positive, the area to its left is less than 0.05
7.The number of teachers in community colleges across New York are grouped into a distribution having the classes, 20-34, 35-49, 50-64, 65-79 and 80-94.

Name the: 

a）Class limits

b）Class Marks

c）Class Width

Part III. 统计学的基本概念代写

Application of Concepts – 5-6 points (5- questions on midterm)

1.

Eleanor scores 680 on the mathematics part of the SAT.  The distribution of SAT scores in a reference population is normal with mean 500 and standard deviation 100.  Joan takes the American College Testing (ACT) mathematics test and scores 27. ACT scores are normally distributed with mean 18 and standard deviation 6.  Find the standardized scores for both students.

Assuming that both tests measure the same math skills who has the higher score?

2.

Speeding: On a stretch of I-89, the mean car speed is 70 mph with a standard deviation of 4 mph.

You are traveling at 76 mph. Approximately what percentage of cars are traveling faster than you?

3.

A set of final examination grades in an introductory statistics course is normally distributed, with a mean of 73 and a standard deviation of 8.  

If a professor grades on a curve (i.e. gives As to the top 10% of the class, regardless of the scores).  

A random variable has a normal distribution with σ= 10.  If the probability that a random variable will take on a value less than 82.5 is .8212, what is the probability that it will take on a value greater than 58.3?

4. 统计学的基本概念代写

The average time to complete a statistics exam in first year graduate psychology students in a local college is 78.5 minutes with a standard deviation of 16.2. 

5.

The average time to complete an essay on climate change is 103.2 minutes with a standard deviation of 11.3 minutes.  Assuming normal distributions, what percentage of the time will the statistics exam take longer than the average time to write the essay, and what percentage of the time will writing the essay take less time than the average time to complete a statistics exam. 

Birth weight

A baby is said to have a low birth-weight when they weigh less than 5 pounds, 8 ounces (2,500 grams). About 8.3% of all U.S. babies born fall into this category.  The mean birth-weight for babies born in the U.S. is about 3,500 grams.

Assuming birth-weights are normally distributed, estimate the standard deviation of birth-weights given this information.

Suppose the U.S. Department of Health and Human Services wants to change the definition of low birth-weight to include only the lowest 5% of birth-weights.

What would be the new definition of a low birth-weight baby? Use the standard deviation you calculated.

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