Share
Explore BrainMass

Normal Distribution

normal distribution

25. A major department store has determined that its customers charge an average of $500 per month with a standard deviation of $80. Assume the amounts of charges are normally distributed. a. What percentage of customers charges more than $380 per month? P(x > 380) = 1- p(x<380) (P(x<380) =

Choice of Statistical Method

Imagine that you are charged with comparing results of standardized tests from four different school districts. What statistical technique would you choose to use? Explain what data you would use to do the comparisons.

Probability of an Event Regarding Normal Distribution

Please see the attached questions regarding Z-Tables. Can you please explain how you get from P(Z<8/3) - P(Z<-8/3) to 0.9962 - 0.0038? How do you check the z-table to find these values? Please show me in the Example Z-Table attached.

Percentile of a normal distribution..

Engineers want to design seats in commercial aircraft so that they are wide enough to fit 98% of all males. (Accommodating 100% of males would require very wide seats that would be too expensive.) Men have hip breadths that are normally distributed with a mean of 14.4 in. and a standard deviation of 1.0 in. (based on anthropom

Women's heights standard deviation

In this exercise, use this information (based on data from the National Health Survey): - Women's heights are normally distributed with mean 63.6 in. and standard deviation 2.5 in. Height Requirement for Women Soldiers The U.S. Army requires women's heights to be between 58 in. and 80 in. Find the percentage of women meeti

Areas under any normal curve

Assume that x has a normal distribution, with the specified mean and standard deviation. Find the indicated probabilities. 6)P(40 less than or equal to x less than or equal to 47); u = 50; o = 15 10) P( x greater than or equal to 2); u = 3; o = 0.25 Find the z value described and sketch the area described. 14) find

Statistics and Uniform Distribution

The figure below graphs the density curve of a uniform distribution. Answer the following Questions ... Too much cholesterol in the blood increases the risk of ... (Please see the attached document) The figure below graphs the density curve for a uniform distribution. Use areas under this density curve to answer the fol

Statistics of Temperature Values

Finding Temperature Values. In this exercise, assume that the readings on the thermometers are normally distributed with a mean of 0o and a standard deviation of 1.00oC. A thermometer is randomly selected and tested. In this case, draw a sketch, and find the temperature reading corresponding to the given information. If 1

Basis for Empirical Rule

In this exercise, find the indicated area under the curve of the standard normal distribution, then convert it to a percentage and fill in the blank. The results form the basis for the empirical rule. About _______% of the area is between z = -3.5 and z = 3.5 (for within 3.5 standard deviations of the mean).

Statistics problem

The manager of the Tee Shirt Emporium reports that the mean number of shirts sold per week is 1,210, with a standard deviation of 325. The distribution of sales follows the normal distribution. What is the likelihood of selecting a sample of 25 weeks and finding the sample mean to be 1,100 or less?

Sampling distribution of a proportion..

Suppose a population proportion is .40, and 80% of the time when you draw a random sample from this population you get a sample proportion of .35 or more. How large a sample were you taking? Please provide answer via excel.

Calculate population and percentages

A large population of metal rods have an average diameter of .943 inches with a standard deviation of .001 inches. The engineering specification for the rods requires that they be between .941 and .944 inches. Using the standardized normal table, determine the percentage of the population that should meet the requirement. Draw a

Solve: 95th Percentile of a Normal Distribution

Question: The monthly sales of mufflers in the Richmond, VA area follow the normal distribution with a mean of 1200 and a standard deviation of 225. The manufacturer would like to establish inventory levels such that there is only a 5 percent chance of running out of stock. Where should the manufacturer set the inventory levels?

Probability: Sampling Distribution

1. Scores for men on the verbal portion of the SAT test are normally distributed with a mean of 509 and a standard deviation of 112. Randomly selected men are given the Columbia Review Course before taking the SAT test. Assume that the course has no effect. If 1 of the men is randomly selected, find the probability that his scor

Normal Distribution

It is said that sufferers of a cold virus experience symptoms for 7 days. However, the amount of time is actually a normally distributed random variable whose mean is 7.5 days and whose standard deviation is 1.2 days. a. What proportion of cold sufferers experiences less than 4 days of symptoms? b. What proportion of cold

Probability using normal distribution: heights of children

The heights of children 2 years old are normally distributed with a mean of 32 inches and a standard deviation of 1.5 inches. Pediatricians regularly measure the heights of toddlers to determine whether there is a problem. There may be a problem when a child is in the top or bottom 5% of heights. Determine the heights of 2 year

Normal distribution and Hypothesis Testing

Problem:1 Suppose that x is normally distributed random variable with µ = 11 and variance = 4. Find each of the following: a)P(10<x <12) b)P(x > 13.24) c)P(x < x0) 0.75 find Xo Problem:2.Consider the following hypothesis test. Ho: µ >; 10 Ha: µ < 10 A sample with n = 50 provides a sample mean of 9.46 and samp

Probability using Normal Distribution

Using the normal distribution, answer the following questions. 1. A pharmaceutical drug has mean effective duration of 10.4 hours with a standard deviation of two hours. In what percentage of the patients will the effectiveness of the drug be: a) Greater than 13 hours? b) At least 9 hours? c) Between 11.8 and 14.6 hour

Bell Curve Chart: The Number of Men Needed

Create a bell curve chart that shows the number of men needed per day for a 10,000 man hour job. The start date is 1/1/2008 and the end date is 6/1/2008. The job will run for a total of 21.71 weeks and there will be 108.57 work days. The estimated man hours is 10,000 and each worker will work an 8 hour shift 5 days out of the we

Probability and Probability Distribution

1. customers in a bank A bank has a drive thru service. The number of customers arriving during a 15 minute period is distributed as shown. Find the mean, variance, and standard deviation for the distribution Number of customers X 0 1 2 3 4 Probability

Statistics - Normsdist and Tdist

Here are tables of the Standard Normal and Student's t distributions. The formulas for the first value in each P column are, respectively =NORMSDIST(A3) and =TDIST(C3,20,2), where column A is the one labeled "Z" and column C is labeled "t". "t". 1. What is the meaning of the number given in the P column under NORMSDIST? 2)

Normal Distribution: Length of a Typical Baseball Game

Assume that the length of a typical televised baseball game, including all the TV timeouts, is normally distributed with a mean of 2.45 hours and standard deviation of 0.37 hour. Consider a televised baseball game that begins at 2:00 in the afternoon. The next scheduled program broadcast starts at 5:00. a. What is the probabi

Mensa - Normal Distribution

To become a member of Mensa, one has to pass the qualifying exam. If the scores on the exam are normally distributed with a mean of 80 and a standard deviation of 25, and if only the top 20% of the people taking the exam are admitted, what is the passing score?

Normality and business research

1. R.C. Geary wrote some 70 years ago that "Normality is a myth. There never was, is, nor will there ever be a Normal distribution". What do you think he meant and what relevance does it have to your work?(Read the Week 2 Lecture 1 before answering) 2.How do you feel that the inferential statistical technique of Hypothesis Te

Statistics - Normal Distribution for Z Scores

Assuming that x has a normal distribution, find the indicated probability a) p(40<_x<_47) mean=50, stand.dev.=15 and p(x_>2)mean=3stand.dev.=0.25 b) Find z value and sketch the are described 1) 97.5%of normal curve lies to the left of z 2) Find z such that 95% of standard normal curve lies to the right of z

How much should a healthy kitten weigh?

How much should a healthy kitten weigh? A healthy 10-week-old (domestic) kitten should weigh an average of mu = 23.5 oz with 95% of data ranging from 13 to 34 oz. Let x be a random variable that represents the weight (in ounces) of a healthy 10-week-old kitten. Assume that x has a distribution that is approximately normal. m

Normal Distribution and Z-Scores

1. For each of the following z-scores, sketch a normal distribution and draw a vertical line at the location of the z-score. Then, determine whether the tail is to the right or the left of the line and find the proportion in the tail. a. z = 2.00 b. z = 0.50 c. z = -1.00 d. z = -0.75. 2. The distribution of score