Explore BrainMass


Four statistics and probability questions

10. The following examples are experiments and their associated random variables. In each case identify the values the random variable can assume and state whether the random variable is discrete or continuous. a. Take a 20-question exam Number of questions answered correctly b. Observe cars arriving at a tollbooth f

6 probability and statistics questions

CH3 Problem 50 The mean income of a group of sample observations is $500; the standard deviation is $40. According to Chebyshev's theorem, at least what percent of the incomes will lie between $400 and $600? CH3 Problem 62 The Citizens Banking Company is studying the number of times the ATM located in a Loblaws Supermarket

Waiting Line Model, Poisson Distribution, Exponential Distribution

A crew of mechanics at the San Jose Transportation Department garage repair vehicles that break down at an average of ë= 7.5 vehicles per day (Poisson Distribution). The crew under the supervision of the VTA city manager can service an average of ì= 10 vehicles per day with a repair time distribution that approximates an expo

Sampling and Business Research

Can type of sampling (probability, non-probability sampling) also affect the results of business research? Explain your answer.

The solution to Normal approximation to the binomial

A summer resort boast that 85% of its new visitors return the next five years. Use the normal approximation to the binomial to find the probability that, of 250 new visitors this summer, at least 200 will return some time within the next five years.

Probability Questions

Chapter 4, page 159, exercise 25 A local bank reports that 80 percent of its customers maintain a checking account, 60 percent have a savings account, and 50 percent have both. If a customer is chosen at random, what is the probability the customer has either a checking or a savings account? What is the probability the customer


A poll of 1,250 investors conducted, assume that 50% of the investors found the market less attractive to the prior years. P=.5, find the probability that the sample proportion obtained from the sample of 1,250 investors would be: A. within 4% points of the population, that is P(.46<^p<.54). B. within 2% points of the pop

Calculation of probability and Chebychev inequality

Please help with the following problem regarding probability. Provide calculations and explanations. 1. The probability of contracting the kissing disease is .23 when one is exposed to a certain provocative environment. Sixty people are so exposed. What is the probability that no more than 10 are infected with this dreaded d

Normal Probability/ Testing Hypothesis

The listed sample distances (in millimeters) were obtained by using a pupilometer to measure the distances between the pupils of adults (based on data collected by a student of the author) 67 66 59 62 63 66 66 55 ~ a) Find the mean x of the distances in this sample. b) Find the median of the distances in this samp

Interpreting Marginal Effects after the Probit Model

Interpreting Marginal Effects after the Probit Model: I have ran a Probit regression, then computed the Marginal Effects after Probit. I want to interpret the effects of men, education, and experience on the model. How does one make quantitative interpretations for this scenario? The output is below: Marginal effect

Statistics Problems based on Chebyshev Inequality

1. In an exam, the mean score is 70 and the variance is 16. What is the probability that a student's score will lie within the "54 to 86" range? (Hint: Use Chebyshev's inequality, as we saw in class). What percentage of students will lie within 2 standard deviations on either side of the mean score? 2. You are the CEO of a

Probability and Statistics question

Each salesperson at stiles compton is rated either below average, average, or above average with respect to sales ability. Each salesperson is also rated with respect to his or her potential for advancement: either fair, good or excellent. These traits for the 500 sales people were cross classified into the following table.

Poisson Distribution

True or false: Suppose that the number of airplanes arriving at an airport per minute is a Poisson process. The average number of airplanes arriving per minute is 3. The probability that exactly 6 planes arrive in the next minute is 0.0504.

Calculating Probability in a Normally Distributed Sample

The number of column inches of classified advertisements appearing on Mondays in a certain daily newspaper is normally distributed with a population mean of 320 and a population standard deviation of 20 inches. 1. Referring to the table above, for a randomly chosen Monday, what is the probability there will be less than 340

Binomial Distribution and NC Army National Guard

In the military, everything works of numbers. Recruiting is a good example of a binomial distribution. I'll use NC Army National Guard for an example. The NCARNG must have a set number of enlistments every year and they get the requirement for the year during October. This year the number is: 2000 (so n = 2000), the 2 ou

Binomial Probability Distribution and Probability

1. Suppose that the number of cars, X, that pass through a car wash between 4:00pm and 5:00pm on any sunny Friday has the following probability distribution: X 4 5 6 7 8 9 P(X=x) 1/12 1/12 ¼ ¼ 1/6 1/6 What is the probability that at least 7 car

Normal approximation to binomial

A multiple-choice examination consists of 90 questions, each having possible choices a, b, c, d, and e. Approximate the probability that a student will get at least 21 answers correct if she randomly guesses at each answer. (Note that, if she randomly guesses at each answer, then the probability that she gets any one answer corr

Statistical Process Control Help

1. A medical supplies company buys its supplies in bulk and redistributes them to doctor's offices and clinics. They receive thermometers in lots of 500 from the vendor. They are considering a sampling plan of n=50 and c=1. a. Develop a OC curve for this sampling plan. (Use Poisson Tables) b. If an incoming lot has 5% defectiv

find the mean and standard deviation

The below table lists the last digits of the 73 published distances (in feet) of the 73 home runs hit by Barry Bonds in 2001 when he set the record for the most home runs in a season (based on data form USA today) The last digit of a data set can sometimes be used to determine whether the data have been measured or simply report


Express the indicated degree of likelihood as a probability value. *"it will definitely turn dark tonight." a. 0.5 b. 1 c. 0.30 d. 0.67 *Which of the following can not be a probability? a. 1 b. 0 c. -1 d. 2 *Answer the question,considering t

Quantitative Methods - should a plane go commercial probability

Management is considering going live with a new product that research believes is promising. Engineering estimates that if a $300,000 pilot plant is build there is a 0.75 chance of a high yield versus the alternative of a low yield. If the pilot plant shows a high yield they believe there is a probability of 0.8 that the comm

Waiter's Probability for Commission

John has two jobs. For daytime work at a jewelry store he is paid $200 per month plus a commission. His monthly commission is normally distributed with a mean of $600 and a standard deviation of $40. At night he works as a waiter, for which his monthly income is normally distributed with a mean of $100 and a standard deviation o

Normal approximation to the binomial distribution

A. Tossing a Coin Simulate 6 independent tosses of a fair coin. Repeat the procedure to get 200 sets of 6 coin tosses. (That's 1200 total tosses.) List the results. Explain carefully your method of simulating the tosses, whether it involves a computer, a table of random digits, or even flipping several coins at once. Addre

Standard distribution

Assume that the population of heights of male college students is approximately normally distributed with mean m of 68 inches and standard deviation s of 3.75 inches. A random sample of 16 heights is obtained. d. Find the mean and standard error of the xbar distribution. e. Find P (xbar > 70) f. Find P ( xbar < 67) I kno