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# Normal Distribution

### Finding the distribution to use to test

Need help finding the distribution If you expect 50/50 split among gender in a particular population and you get 60/40 on one sample which distribution would you use to test if the proportions are actually different?

### Statistics - significance and use of the normal curve

Consider the relationship between derived scores and the normal curve. In terms of the normal curve and how it relates to psychological testing and assessment. "Consider real-world applications of the normal curve."

### Solving a sampling distribution problem

The population of fruit cans filled by a particular machine is known to be normally distributed with a mean equal to 12 ounces and a standard deviation equal to .25 ounces. Given this information, the sampling distribution for a random sample of n = 25 cans will also be normally distributed with a mean equal to 12 ounces and a s

### Sampling distribution of proportions

The president of Doerman Distributors, Inc., believes that 34% of the firm's orders come from first-time customers. A simple random sample of 120 orders will be used to estimate the proportion of first-time customers a. What is the probability that the sample proportion will be between .25 and .35 (to 4 decimals)? Time/CNN

### Student's t and Standard Normal Comparison

1. Chapter 8: (a) Chapter Review question # 10 (0.5 point) List differences and similarities between the Student's t and the standard normal distribution and carefully show all steps in your response. (b) Chapter Review question # 11 (0.5 point) By means of an example, show that for a given confidence le

### What are the normal distribution probabilities for Weston Materials, Inc. and Shaver Manufacturing, Inc.?

Problem Sets - Descriptive Statistics and Probability Distributions Statistical Techniques in Business & Economics (text) 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

### Selection of a tail test impact

1) How might the selection of a given tail test impact the Type I or II error, if any? 2) If the problem itself is not yet stated how might a researcher know which type of -tail test to use? 3) Might there be instances where a test is looking for a section of the area under the curve and not just the extreme ends?

### The Rejection Region for a Two-Tail Test

The rejection region for a two-tail test that uses the standard normal distribution is that area under the distribution lying: a. between 0 and the positive cutoff value for Z. b. between the positive cutoff value for Z and the negative cutoff value for Z. c. between 0 and the negative cutoff value for Z. d. to the right

### A Manufacturer's Production Policy

The manufacturer of a particular bicycle model has the following costs associated with the management of the product's inventory. In particular, the company currently maintains an inventory of 1000 units of this bicycle model at the beginning of each year. If X units are demanded each year and X is less than 1000, the excess sup

### Normal Distribution

Which of the following about the normal distribution is not true? a. About 2/3 of the observations fall within ±1 standard deviation from the mean. b. Its parameters are the mean, &#956;, and standard deviation, &#963;. c. It is a discrete probability distribution. d. Theoretically, the mean, median, and mode are the same

### The Normal Distribution

In its standardized form, the normal distribution a. has an area equal to 0.5. b. has a mean of 0 and a standard deviation of 1. c. has an area equal to 100. d. has a mean of 1 and a variance of 0.

### Calculating Probability Based on the Normal Distribution

Assume that women's heights are normally distributed with a mean given by u=64.2in, and a standard deviation given by o=2.3in. A) If one woman is randomly selected, find the probability that her height is less than 65in. (Round to four decimal places as needed). B) If 33 Women are randomly selected, find the probability th

### Normal distributions

Part A: Describe the properties of a normal distribution. Explain why there are an infinite number of normal distributions. How does a standard normal distribution differ from any from any other normal distribution, and how is it similar? Explain. Part B: What is the transformation to standardize a normal random variable? Why

### What percentage of architects have Z scores (a) above .10, (b) below .10, (c) above .20, (d) below .20, (e) above 1.10, (f) below 1.10, (g) above -.10, (h) below -.10?

Suppose that the scores of architects on a particular creativity test are normally distributed. What percentage of architects have Z scores (a) above .10, (b) below .10, (c) above .20, (d) below .20, (e) above 1.10, (f) below 1.10, (g) above -.10, (h) below -.10?

### Normal distribution applied to baseball

5. In baseball, a "no-hitter" is a regulation 9-inning game in which the pitcher yields no hits to the opposing batters. Chance (Summer, 1994) reported on a study of no-hitters in Major League Baseball (MLB). The initial analysis focused on the total number of hits yielded per game per team for all 9-inning MLB games played betw

### Normal Distribution Characteristics

1. True or False? Replacement is allowed in binomial experiments. Explain your answer. 2. True or False? Two normal distributions that have the same standard deviation have the same shape, regardless of the relationship between their means. Explain your answer.

### Fast Service Truck Lines uses the Ford Super Duty F-750 exclusively. Management made a study of the maintenance costs and determined the number of miles traveled during the year followed the normal distribution. The mean of the distribution was 60,000 miles and the standard deviation 2,000 miles.

Fast Service Truck Lines uses the Ford Super Duty F-750 exclusively. Management made a study of the maintenance costs and determined the number of miles traveled during the year followed the normal distribution. The mean of the distribution was 60,000 miles and the standard deviation 2,000 miles. a. What percent of the Ford S

### Solving normal problems with Excel

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. Assume the assembly times follow the normal distribution. a. Determine the z values for 29 and 3

### Understanding the z-score.

The standard normal table shows an area value of 0.1 for a z-score of 0.25 and an area value of 0.35 for a z-score of 1.04. What percentage of the observations of a random variable that is normally distributed will fall between 0.25 standard deviations below the mean and 1.04 standard deviations above the mean? a. 25% b. 35%

### Targeted Hold Time - statistics

What fraction of the days in April 2005 failed to meet the targeted hold time of 110 seconds? Given the dail average hold time after process improvements was normally distributed with a mean of 79.50 and a standard deviation of 16.86, what fraction of days where the call center failed to meet the targeted hold time of 110 secon

### Sample Question: Probability using normal distribution

A traffic study at one point on an interstate highway shows that vehicle speeds are normally distributed with a mean of 61.3 mph and a standard deviation of 3.3 mph. If a vehicle is randomly checked, find the probability that its speed is between 55.0 mph and 60.0 mph.

### Statistics Study Guide 2

1. Which of the following statement(s) about the normal probability distribution is/are true? a. The mean equals the mode and the median b. The median equals the mode c. The mean divides the distribution into two equal parts d. All of the above e. None of the above 2. a. 375 and 425 b. 300 and 500 c. 390 and 410

### Important information about Statistics - Normal Distribution

The average length of stay in a chronic disease hospital for a certain type of patient is 60 days with a standard deviation of 15. Suppose it is reasonable to assume an approximately normal distribution of legths of stay. a) What percentage of patients stay less than 50 days? Fill in the blanks .... (Please see the at

### Normal probability distribution: Using the normal probability distribution, what is the probability the car will be repaired in 35 minutes or less?

An auto repair shop takes an average of 45 minutes to complete a repair job. The owner of the shop has determined the repair time has a standard deviation of 7 minutes. A customer comes into the shop and states that she will return in 35 minutes -- at which time she must have the car ready to drive off. Using the normal probab

### Definition of a Probability Distribution

A probability distribution a. Is a listing of all possible values of a random variable. b. Is a listing of all possible values of a random variable, along with the probabilities. c. Can assume values between -1 and +1. d. Has none of the above properties.

### The control charts checking errors

Problem 1 A store has noticed that checking errors have been occurring. The question arose as to whether these errors are any different than has happened in the past. An employee suggested that control charts be used to monitor this process. Fortunately there were past records which shoed that the average number of errors were

### Probabilistic Design using Factor of Safety Method.

See attached Probabilistic design using yield stress as the failure criterion must be accomplished...what minimum safety factor is acceptable?

### Calculating Probabilities from a Normal Distribution

If x is normally distrubed with u = 20.0 and o = 4.0, determine the following: a. P(x > 20.0) b. P(16.0 < x < 24.0) c. P(X < 12) d. P(x = 22.0) e. P(12.0 , x , 28.0) f. P(x 15)

### Deriving Z-value from a normal distribution

Using the standard normal table, determine a z value (to the nearest two decimal places)such that the area: a. from the midpoint to z is 0.20 b. from the midpoint to z is 0.48 c. between z and negative infinity is 0.54 d. between z and positive infinity is 0.30

### Probability questions

1) The manufacturing of a ball bearing is normally distributed with a mean diameter of 22 millimeters and a standard deviation of .016 millimeters. To be acceptable the diameter needs to be between 21.97 and 22.03 millimeters. a. What is the probability that a randomly selected ball bearing will be acceptable ? (Round to tent