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# Normal Distribution

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### 1 question statistics

Best Electronics, Inc. offers a "no hassle" returns policy. The number of items returned per day follows the normal distribution. The mean number of customer returns is 10.4 per day and the standard deviation is 2.3 per day. (a) In what percent of the days are there 7.5 or fewer customers returning items? (Round z-score co

### Normal Distribution, Z-Score and Percentage

Suppose a botanist grows many individually potted eggplants, all treated identically and arranged in groups of four pots on the greenhouse bench. After 30 days of growth, she measures the total leaf area Y of each plant. Assume that the population distribution of Y s approx. normal with mean=800cm^2 and SD=90cm^2. a) What per

### Estimating the first-time customers from a random sample

The president of Doerman Distributors, Inc., believes that 26% of the firm's orders come from first-time customers. A simple random sample of 80 orders will be used to estimate the proportion of first-time customers. Assume that the president is correct and p = 0.26. What is the sampling distribution for this study? Select

### 8 Statistics problems: Discrete Distributions and Continuous Distributions

This project is based on Discrete Distributions and Continuous Distributions. Question # 7 does not have to be an elaborate study, just something basic, a study that you might conduct at work. 1. What are the characteristics of a normal distribution? 2. Determine the probability or area for the portions of the normal distr

### Normal Distribution of mean height of males: probability

Write a paragraph about the normal distribution. In the paragraph give an example of a distribution that you would judge to be nearly normal and explain why you have made that conclusion. Estimate the mean of this distribution and the standard deviation. Then estimate a probability based upon those values: (E.g., average height

### Probabilities based on normal distribution.

In a study of how external clues influence performance, psychology professors at the University of Alberta and Pennsylvania State University gave two different forms of a midterm examination to a large group of introductory psychology students. In one form of the exam the questions were printed on blue paper, and in the othe

### Statistics: Customer satisfaction and loyalty at Bank of America

3. Quality Progress, February 2005, reports on improvements in customer satisfaction and loyalty made by Bank of America. A key measure of customer satisfaction is the response (on a scale from 1 to10) to the question: "Considering all the business you do with Bank of America, what is your overall satisfaction with Bank of Ameri

### Normal Distribution and Z-Score: Finding Probability

1.The amounts of money requested on home loan applications at a particular bank follow the normal distribution, with a mean of \$80,000 and a standard deviation of \$24,000. A loan application is received during the day. By hand: a. Find the probability that the amount requested amount is \$90,000 or more? b. Find the proba

### Statistics Problem: Armstrong Faber Pencil Production and Sales

Armstrong Faber produces a standard number-two pencil called Ultra-Lite. Since Chuck Armstrong started Armstrong Faber, sales have grown steadily. With the increase in the price of wood products, however, Chuck has been force to increase the price of the Ultra-Lite pencils. As a result, the demand for Ultra-Lite pencils has been

### Number of homes runs hit by the American League: mean and standard deviation

5 The following table gives the number of homes runs hit by the American League home-run champions for the years 1949 to 1987, given in chronological order beginning with 1949 and proceeding left to right across the rows. (Source: Time Almanac 2004, page 1010.)

### Statistics: 6 practice problems

1. For a normal distribution, find the z-score values that separate A. The middle 60% of the distribution from the 40% in the tails. B. The middle 70% of the distribution from the 30% in the tails. C. The middle 80% of the distribution from the 20% in the tails. D. The middle 90% of the distribution from the 10% in the tail

### Statistics Problems: Normal Distribution, Central Limit Theorem

See attached file. #1. Z is N 17. I distributed. Find (a) P( Z < .6); (b) P( Z <= -.03); (c) P( .12 < Z <= 2.14); (d) P( -1.67 <= Z < 1.20) #2. X is N -10.16 distributed. Find (a) P(X> -12); (b) P(-ll < X <= -8); (c) P(IX+ 101<2); (d) P(IX+lll> 1.5) #4. Suppose that the length X of a random bolt produced by machine A

### Weston Materials: Determining Z Values

Please post in Excel Format. Each response must include your calculations. The accounting department at Weston Materials, Inc., a national manufacturer of unattached garages, reports that it takes two construction workers a mean of 32 hours and a standard deviation of 2 hours to erect the Red Barn model. A

### P-value of a Test Significance applet for 'acid rain' in the atmosphere; NAEP test scores

Please see attachment and explain all work. #1 Emissions of sulfur dioxide by industry set off chemical changes in the atmosphere that results in "acid rain." The acidity of liquids is measured by pH on a scale of 0 to 14. Distilled water has a pH of 7.0, and lower pH values indicate acidity. Normal rain is somewhat acidic,

### Population has normal distribution with a mean

A population of scores forms a normal distribution with a mean u=40 and a standard deviation of sigma= 12. What is the probability of randomly selecting a score less than x=34. Please set up this problem what is the formula for this?

### Normal distribution with standard deviation for Douglas Fir wood pieces (Please see attachment and show all work).

How heavy a load (pounds) is needed to pull apart pieces of Douglas fir 4 inches long and 1.5 inches square? Here are data from students doing a laboratory exercise... a) We are willing to regard the wood pieces prepared for the lab session as an SRS of all similar pieces of Douglas fir. Engineers also commonly assume that ch

### Normal Probability and Distribution: Viewers of American Idol

The number of viewers of American Idol has a mean of 29 million with a standard deviation of 5 million. Assume this distribution follows a normal distribution. What is the probability that next week's show will have (a) between 30 and 34 million viewers (b) have at least 23 million viewers and (c) exceed 40 million viewers?

### Determining Percent of Observations within Given Ranges

The mean of a normal probability distribution is 60. The standard deviation is 5. About what percent of the observations lie between 55 and 65 About what percent of the observations lie between 50 and 70 About what percent of the observations lie between 45 and 75

### Normal Probability:Sampling Distribution of SampleProportion

For a certain product, Curtis, Inc.'s brand has a market share of 30%. Suppose a survey of 1000 consumers of the product asked which brand they prefer. What is the probability that more than 32% of those surveyed will say that they prefer the Curtis brand?

### Normal Distribution: Raw scores

Suppose we have a population of scores with a mean (mu) of 200 and a standard deviation (sigma) of 10. Assume that the distribution is normal. Provide answers to the following questions: 1. What score would cut off the top 5 percent of scores? 2. What score would cut off the bottom 5 percent of scores? 3. What scor

### Proportion of population considered to be potential leaders

Normal distribution: Word problems An aptitude test is designed to measure leadership abilities of the test subjects. Suppose that the scores on the test are normally distributed with a mean of 580 and a standard deviation of 120. The individuals who exceed 700 on this test are considered to be potential leaders. What propor

### Normal Distribution: Heights of Adult Women in the US

Normal distribution raw scores Suppose that the heights of adult women in the United States are normally distributed with a mean of 64.5 inches and a standard deviation of 2.4 inches. Jennifer is taller than 90% of the population of U.S. women. How tall (in inches) is Jennifer? Carry your intermediate computations to at leas

### What is the value of c such that P(Z <= c) = 0.1271?

Standard normal values: Basic Let Z be a standard normal random variable. Use the calculator provided to determine the value of c such that P (Z <= c) = 0.1271 Carry your intermediate computations to at least four decimal places. Round your answer to at least two decimal places.

### Z-scores & Decision Making

Suppose you earned 100 points on an exam. Under which of the following conditions did you earn the best grade? Please explain this to me. When: a. ? = 80 and Ï? = 10 b. ? = 80 and Ï? = 5 c. ? = 105 and Ï? = 10 d. ? = 105 and Ï? = 5

### General Statistics Probability for Cumulative Distribution

1. The age of cars in the staff parking lot of a suburban college is uniformly distributed from six months (0.5 years) to 9.5 years. a) What is being measured here? Age of cars b) In words, define the Random Variable X. c) Are the data discrete or continuous? continuous d) The interval of values for X is: (0.5, 9.5) e) The

### Normal distribution department of health

According to the South Dakota Department of Health, the mean number of hours of TV viewing per week is higher among adult women than men. A recent study showed women spent an average of 34 hours per week watching TV and men 29 hours per week (http://www.state.sd.us/DOH/Nutriton/TV.pdf). Assume that the distribution of hours watc

### Sampling distribution for means and sums

In exercise 6.8 we considered an automobile insurer whose repair claims averaged \$927 over the past with a standard deviation of \$871. A random sample of 50 new claims is taken. a. Describe the sampling distribution for ?. b. Use normal approximation to calculate P(? > 1100). The ? is a capital with a line above. I thi

### Statistics - Multiple Choice Questions

1. On an exam with s = 6, Tom's score of X = 54 corresponds to z = +1.00. The mean for the exam must be m = 60. (Points: 1) True False 2. A population with m = 45 and s = 8 is standardized to create a new distribution with m = 100 and s = 20. In this transformation, a score of X = 41 from the original distr

### Locate a z score for 1.645 associated with an alpha of .05

Locate a z score for 1.645 associated with an alpha of .05 using standard normal areas statistical tables. Then, using a Student's t distribution statistical table, find the 1.645 value. Explain why the t distribution approaches the z distribution as the sample size gets larger.

### Population Mean Corresponding

6. For a population with a mean of µ =100 and standard deviation of Ï? =10, a. X =105 X=120 X = 130 X = 90 X = 85 X =60 b. Find the score (X value) that corresponds to each of the following z-scores. z = 1.00 z = -0.50 z = 2.00 z = 0.70 z = 1.50