Explore BrainMass

Normal Distribution


1. Last year, at Northern Manufacturing Company, 200 people had colds during the year. One hundred fifty-five people who did no exercising had colds, while the remainder of the people with colds were involved in a weekly exercise program. Half of the 1,000 employees were involved in some type of exercise. a. What is the proba

Plot and Analyze Data: Absorbance for the Iron-Bipyridyl Complex

Please see attached file for the data. The following data were collected on absorbance for the iron-bipyridyl complex as a function of iron concentration in parts per million. Seven groups undertook the experiment. Question 1 In Excel calculate the mean and associated 95%CL for each concentration and then plot these dat

Statistics: Normal Distribution, Rule, Normal Body Temperature

1. Which of the following statements are correct? a. A normal distribution is any distribution that is not unusual. b. The graph of a normal distribution is bell-shaped. c. If a population has a normal distribution, the mean and the median are not equal. d. The graph of a normal distribution is symmetric. Using the 68-

Statistics: Investment Digest for mean of annual return for common stocks

Please provide answers and explanations in Excel spreadsheet. 1. According to Investment Digest ("Diversification and the Risk/Reward Relationship", Winter 1994, 1-3), the mean of the annual return for common stocks from 1926 to 1992 was 15.4%, and the standard deviation of the annual return was 24.5%. During the same 67-

Typical Seasonal Demand for Summer Highs

1. Compute the standard deviation in Microsoft Excel using the data (raw data from years 1-4) 2. Generate a normal distribution of the data using Microsoft Excel. 3. Compare the range with the standard deviation of the data. Typical Seasonal Demand for Summer Highs Actual Demands (in units) Month Year 1

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: 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

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

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 ( 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

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

Statistics: Multiple Choice Questions

1. An economist is interested in studying the incomes of consumers in a particular region. The population standard deviation is know to be $1,000. A random sample of 50 individuals resulted in an average income of $15,000. What sample size would the economist need to use if he wants a 95% confidence interval no wider than plu

Normal Distribution

A) What is normal distribution? b) given a certain data set, how can you determine whether the data set is normally distributed or not? c) Why do we want to test if the data is normally distributed?


Confidence Interval Estimation 2. Compute a 95% confidence interval for the population mean, based on the sample 15, 17, 13, 14, 15, 14, and 59. Change the number from 59 to 14 and recalculate the confidence interval. Using the results, describe the effect of an outlier or extreme value on the confidence interval.

Plot the vehicle stopping distance versus the speed of travel

Question 1 The distance Y necessary for stopping a vehicle is a function of the speed x of the vehicle. Suppose the following set of data were observed for 12 vehicles travelling at different speeds as shown in the table below. Vehicle No. Speed, kph Stopping Distance, m 1 40 15 2 9 2 3 100 40 4 50 15 5 15 4 6 65 25

Research and Evaluation: Example Problem

What are some examples of literature reviews and statistics used and available at your work place or organization? What are they used for and how are they determined? What are the advantages and disadvantages of using surveys to conduct research? What is an example of a loaded question? In what situations is it appropriate t

Consider a random variable, z, that has a standardized normal distribution. Determine the following probabilities: Bowser Bites Industries (BBI) sells large------standard deviation of 1.25 kilograms. What is the probability that a filled bag will weigh less than 49.5 kilograms?

Can you please assist with questions 6-11 and 6-17 putting the answers and solutions in an excel spread sheet. 6.11 ) Consider a random variable, z, that has a standardized normal distribution. Determine the following probabilities: a) P(0<z<1.96) b) P(z>1.645) c) P(1.28<z<2.33) d) P(-2<z<3) e) P(z>-1) 6.17 ) Bow