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Normal Distribution

Normal Distribution - Sheet Metal Stamping Machine

For the sheet-metal stamping machine in a certain factory, the time between failures, X1 has a mean between the failures, of 56 hours and a variance of 16 hours. The prepair time X2, has a mean time to repair of 5 hours and a variance of 4 hours. a) If X1 and X2 are independent , find the expected value and the variance of Y

Normal Distribution - Confidence Limits

The mean amount of a purchase at the Smith Hardware store is $23.50 with a standard deviation of $5.00. The amounts purchased follow a normal distribution. 50 customers were sampled: a.What is the likelihood the sample mean is at least $25.00? b.What is the likelihood the sample mean will fall into the $22.50 to $25.00 range

Probability Percentage: Normal Distribution & Standard Deviation

According to a retail electronics chain, adults in the 40 to 50 year old age group, the mean amount spent per year on electronics is $1998. Assume that the amount spent follows a normal distribution with a standard deviation of $550. a. What percent of adults in this age group spend more than $2500 per year on electronics? b

What does it mean to say that x = 152 has a standard score of +1.5?

A. What does it mean to say that x = 152 has a standard score of +1.5? b. What does it mean to say that a particular value of x has a z-score of -2.1? c. In general, what is the standard score a measure of? 6. An animal trainer obtained the following data (Table A) in a study of reaction times of dogs (in seconds) to

Normality Assumptions of Populations

I have completed the problem. But I am knowing how to check the normality assumptions of both population. I used minitab for output. Lesson 10, Practice Problems 1. Problem 6.8: First check assumptions by verification that there are both (1) independent samples from the two populations and (2) that data in each sample are

TESTS OF THE EQUALITY OF TWO NORMAL DISTRIBUTIONS

Please see the attached file. If you have any question or suggestion on my posting, please let me know. Thank you. --------------------------- (The material is from TESTS OF THE EQUALITY OF TWO NORMAL DISTRIBUTION. Please use technological device to solve/draw if you need (preferably Excel or Mathematica), please expla

Weekly Salaries of Teachers: Normal Distribution

The weekly salaries of teachers in one state are normally distributed with a mean of $490 and a standard deviation of $45. a. What is the probability that a randomly selected teacher earns more than $525 per week? b. What is the probability a randomly selected teacher earns less than $435 per week?

Quality Check on Water Bottle Volume

An airline serves bottles of Galena Spring Water that are supposed to contain an average of 10 ounces. The filling process follows a normal distribution with process standard deviation 0.07 ounce. Twelve randomly chosen bottles had the weights shown below (in ounces). (a) Set up a two-tailed decision rule to detect quality c

Sample Sizes, Normal Distribution, and T-Distribution

1. In order to efficiently bid on a contract, a contractor wants to be 99% confident that his error is less than two hours in estimating the average time it takes to install tile flooring. Previous contracts indicate that the population standard deviation o- is 4.5 hours. Find the minimum sample size "n" that is needed to estima

Binomial Probability and Confidence Intervals

(17) A recent study following attrition rates at a major university has shown that 43% of all incoming freshmen do not graduate within 4 years of entrance. If 200 freshmen are randomly sampled this year and their progress is followed, what is the probability that 100 or less will not graduate within the next 4 years. Verify that

Daily output of Marathon's Garyville, Lousiana, refinery is normally distributed with a mean of 232,000 barrels of crude oil per day with a standard deviation of 7,000 barrels.

Daily output of Marathon's Garyville, Lousiana, refinery is normally distributed with a mean of 232,000 barrels of crude oil per day with a standard deviation of 7,000 barrels. (a) What is the probability of producing at least 232,000 barrels? (b) Between 232,000 and 239,000 barrels? (c) Less than 239,000 barrels? (d) Less than

Variables and Normal Distribution

Discuss why you would or would not expect each of the following variables to be normally distributed. Hint:Would you expect a single central mode and tapering tails? Would the distribution be roughly symmetric? Would one tail be longer than the other? a. Shoe size of adult males. b. Years of education of 30-year-old employed

A Discrete and A Continuous Random Variable

Explain the difference between a discrete and a continuous random variable. Give two examples of each type of random variable. Determine whether each of the distributions given below represents a probability distribution. Justify your answer. a) x 1 2 3 4 P (x) 1/8 1/8 3/8 1/8 b) x 3 6 8

The Normal Curve of Distribution: Definition, Shape, Formula

How would you define the normal curve of distribution? Why do you think the normal curve of distribution is a bell shape? Can you please describe and explain the formula for the normal curve of distribution? Also explain the process of hypothesis testing in research creation of hypothesis testing for problem statements, vali

Z-Scores and Normal Distribution

A study of long distance phone calls made from the corporate offices of the Pepsi Bottling Group, Inc., in Somers, New York, showed the calls follow the normal distribution. The mean length of time per call was 4.2 minutes and the standard deviation was 0.60 minutes. a. What fraction of the calls last between 4.2 and 5 minutes?

Defining the Normal Curve of Distribution

I have been given the task to study a group of students that are completing their BA degree in psychology. The main purpose of the study is to find out their level of satisfaction and to identify the most helpful areas provided by the program. Based upon this information formulate: Formulate hypothesis for this problem. I

Online professor's response to: normal distribution

Always get overwhelmed by the amount of material when covered at a comprehensive level. Attached is the study material of what to be prepared to cover at the conclusion of this course. I have worked through them but get stumped at several points. Can you provide a systematic approach to these problems and provide a reference to

Describe the Properties of a Normal Distribution

Describe the properties of a normal distribution. Explain why there are an infinite number of normal distributions. Why do we want to assume that our sample data represent a population distribution?

Tire Manufacturing: Normal Distribution and Standard Deviation

A tire manufacturer believes that the tread life of its snow tires can be described as a normal distribution with a mean of 32,000 miles and a standard deviation of 2500 miles. a. If you buy a set of these tires, would it be reasonable to expect they will last 40,000 miles? What do you base your decision on? b. What perce

Probability calculation Using Normal Distribution Problem

Please help with the following question. Provide step by step calculations. Assume that the number of calories in a McDonald's Egg McMuffin is a normally distributed random variable with a mean of 290 calories and a standard deviation of 14 calories. (a) What is the probability that a particular serving contains fewer than 3

Normal Distribution Standards

Find the standard normal area for each of the following, showing your reasoning clearly and indicating which table you used. a. P(1.22 < Z < 2.15) b. P (3.00 < Z < 2.00) c. P (Z < 2.00) d. P(Z = 0)

Question about Normal Distributions and Z-Scores

Assume that the average annual salary for a worker in the United States is $27500 and that the annual salaries for Americans are normally distributed with a standard deviation equal to $6250. Find the following: a) What percentage of Americans earn below $18000? b) What percentage of Americans earn above $40000?

Solving a Normal Distribution Problem

What are the characteristics of the normal distribution? Why is the normal distribution important in statistical analysis? Provide an example of an application of the normal distribution.