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Normal Distribution

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

Population Distribution Probabilities

A population distribution is normal with a mean of 25 and a standard deviation of 5. If a piece of datum is randomly taken from this distribution, what is the probability that it is less than 20? If a sample of 4 pieces of data are taken from this distribution, what is the probability that the mean will be less than 20?

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

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

Z-Scores, Percentile, and Normal Distributions

The diameters of oranges in a certain orchard are normally distributed with a mean of 5.26 inches and a standard deviation of 0.50 inches. a. What percentage of the oranges in this orchard have diameters less than 4.5 inches? b. What percentage of the oranges in this orchard is larger than 5.12 inches? c. A random sample

Find the equatoin of the least squares regresssion line.

From probability... Distributions of two random Variables. The Correlation Coefficient. Please show each step of your solution. Please check typos and final answers before you post. I will appreciate it. Final Answer from my text book: a= Mu_Y - (Mu_X)*b, b= Cov(X,Y)/(Sigma_X)^2

Normal Distribution - Motorcycles

When you compare the lengths of motorcycles you find the mean to be 65" and the standard deviation is 2.5". You discover your motorcycle is longer than 80% of the motorcycles. How long is your motorcycle?

Description of standard normal random variable

Let z be a standard normal random variable and calculate the following probabilities: p(z is greater than .73) = p(z is less than or equal to 1.75 = p(-1.33 is less than z which is less than 2.2) =

Normal Approximation and Binomial Probability

Please help with the following problem. Past experience indicates that 30% of all individuals entering a certain store decide to make a purchase. Using (i) the binomial distribution and (ii) the normal approximation to the binomial, find that probability that 10 or more of the 30 individuals entering the store in the given h

On average, your department ships an order two hours after it is received.

On average, your department ships an order two hours after it is received. The distribution of times is approximately normal, the standard deviation is 15 mins. -today you handled 120 orders (empirical rule)a. how many orders would you expect to be shipped : within 2 hours of being received --b. within 1 hour 30 mins How ma

Probability Statements and Regression Data

3. Spring-loaded canons are designed to shoot t-shirts into the stands at sporting events. Test firings are conducted on a large level field. The distance that a t-shirt flies is a function of the angle of elevation. When the angle is 35 degrees, the distances follow a normal distribution with a mean of 114.0 feet and a standard

Hypothesis Test for Grocery Receipts

A simple random sample of 100 grocery receipts was drawn from a normal population. The mean and standard deviation of the sample were $120 and $25, respectively. Test the hypothesis H0: u = 125 vs H1:u not = 125 at the 10% significance level. Test Statistic = Critical Values(s) = Conclusion: Interpretation: Plea

Business Management - Audit Analysis and Statistics.

Can and how would you apply basic probability concepts to facilitate business decision making? What is the difference between discrete and continuous probability distributions? How would you apply the normal distribution to facilitate business decision making?

Martin Pullin Inventory Plan Calculations

I need your help in checking my caculation the attached inventory plan table for Martin-Pullin Bicycles Corp. My other calcualtions on the case are also included on the spreadsheet, I now need to calculate the inventory table, (there are two tabs on the spreadsheet). The key thing is to set up the inventory plan correctly, a mon

Crouse Fuse Company: Business + STATs = Operations Management

The Crouse Fuse Company case (attached pdf) presents a problem that may be analyzed with the use of P-Control Charts. The sampling data from operations during the monitored control week are used as a basis for P-Control chart limits in the future. From the data in Exhibit 1 of the case, there are 80 different samples of 5

Normal Distribution and and Cereal Containers

The amount of cereal in a box is not constant, but the distribution can be modeled with a normal distribution with a mean of 16.5 ounces. If the manufacturer is required to fill 90% of the containers with 16 (or more) ounces of cereal, what is the largest allowable value of the standard deviation ?