Explore BrainMass


Normal Probability: Life span of bulbs & Cut off mark..

1). In an examination the mean score was 80, the standard deviation was 10, and the grades followed a normal distribution. The instructor wants to assign A's to the top 12%. Where should the cutoff point for A's be? (2). A company manufactures electric light bulbs that have an average life of 1000 hours and a standard deviati

Probability of Argentina consumer selections

Based on the table given in the attached file: 1. What is the probability that a consumer selected at random purchased fewer products than before? Round to 4 decimal places. 2. What is the probability that a consumer selected at random purchased the same number or more products than before? Round to 4 decimal places. 3

Statistics problem

I need help with these specific questions on my homework. I did the rest but can't figure these out. Please include an explanation because I don't want to get behind by not understanding how to solve these questions. I'm already struggling enough - don't need to add more to it. 1. A distribution has a standard deviation of

Statistics: Five Random Variable problems

Learning objectives: distinguish between discrete and continuous random variable; compute statistics about random variable; compute statistics about a function of a random variable; compute statistics about the sum of a linear composite of random variables; identify which type of distribution a given random variable is most like

Probability - Random Samples

According to the U.S. Census Bureau, the mean household income in the United States in 2000 was $57,045 and the median household income was $42,148 (U.S. Census Bureau, "Money Income in the United States: 2000,", September 2001). The variability of household income is quite large, with the 10th percentile approxi

Probability: Weather, Lottery, Outfits for the Year

1. There is a 20% probability of rain tomorrow means that: a. Tomorrow it will be raining during 0.2 of the day, and the rest of the day it will be clear. b. Out of the next 5 days, one day it will be raining. c. According to the records, if a weather like one we have today occurred in the past, then 20% of cases it w

Statistics: 4 problems about random variables and their probability distributions

3-44 A real estate agent has four houses to sell before the end of the month by contacting prospective customers one by one. Each costumer has an independent 0.24 probability of buying a house on being contacted by the agent. a) If the agent has enough time to contact only 15 customers, how confident can she be of selling a

Statistics M2: Six comprehensive problems

1. An auto supply store uses a fixed order size with safety stock system to control the inventory of a type of motor oil it sells. Demand for the oil averages 20 units per day (7300 units per year) and the standard deviation of the daily demand is 4.3 units. For this item, the cost of placing each order is $35. The store purchas

Statistics: Union and intersection problems

1) Let G be the event that a girl is born. Let F be the event that a baby over 5 pounds is born. Characterized the union and the intersection of the two events? 2) Consider the event that a player scores a point in a game against team A and the event that the same player scores a point in a game against team B. What is the u

Statistics: Tchebychev inequality for samples

The Tchebychev inequality can also be stated in the following way: For any random variable x with mean equal to μ and variance equal to Δ². The minimum probability of X belong to the interval X?[ μ-k, μ+k] is at least: P( | X- μ|<k &#8805; 1-( Δ/k²) Suppose that the random variables x1, x2, x3... xn form a random sa

Poisson distribution probabilities and recursion relationship

The Poisson distribution is given by the following P(x,λ)=e ^ -λ * λ^x! x=0,1,2,3.....j..... Where λ>0 is a parameter which is the average value &#956; in poisson distribution. a) show that the maximum poisson probability P(x=j,λ) occurs at approximately the average value, that is λ=j if λ>1. (hint: you can take t

Statistics: Simulate the emergency calls for 3 days, using a random number table.

Simulate the emergency calls for 3 days, using a random number table. Compute the average time between calls and compare this value with the expected value of the time between calls from tthe probability distribution. Rescue receives an emergency call every 1, 2, 3, 4, 5, or 6 hours, according to the following probability di



Probability of events using a standard deck of playing cards

1. You possess a 'standard deck of playing cards' (n = 52). First, (a) identify the probability of selecting a spade, club, or heart. Second, (b) calculate the probability of selecting a spade, heart, diamond, or face card. Identify (c) the probability of selecting (in sequence) a two and a red jack (assuming that the fi

Probability computation

1. A real estate investor has two houses: A and B. Each house may increase in value, decrease in value, or remain unchanged. Consider the experiment of investing in the two houses and observing the change (if any) in value: a. How many experimental outcomes are possible? b. Show a tree diagram for the experiment.

Calculate probability of different outcomes conditional on favorable reviews

A manufacturing company is trying to decide whether to add a new product line and the marketing department has been asked to help with this decision. Information on previous products produced indicates that 10% are huge successes, 20% are modest successes, 40% break even, and 30% are losers. However before the product decision

Application of Various Tools using Probability Theory

See the attached file. 1) The time it takes for a light bulb to burn out. Continuous The weight of a t-bone steak Continuous The number of people in class who have type B blood. Discrete 2) The mean (expected value) of the random variable is 3) The variance of the random variable is 4) The stand

Decision Trees and portfolio theory

Q1 A company has developed two types of synthetic fuel. However it has not developed efficient manufacturing processes for either of them. It has has the option to develop the manufacturing process for both, either or none of them. They estimate that if they try to develop a process for fuel A then their probability of success

Statistics Questions

1.Blood cocaine concentration (mg/L) was determined both for a sample of individuals who had died from cocaine-induced excited delirium (ED) and for a sample of those who had died from a cocaine overdose without excited delirium (non-ED); survival time for people in both groups was at most 6 hours. The accompanying data comes fr

Conditional probability problems: What is the probability that a student who has failed the test came from the south district? What is the probability that a student from the entire school system, chosen at random, has passed?

1.) a metropolitan school system consists of two districts- north and south. the north district contains 60% of all students, and the south district contains 40% of all students. a minimum competency test was given to all students. 10% of the north district students failed, and 15% of the south district students failed. What


A group of n people meet at lunch for a cup of coffee. They play a game to see who gets to pay for all the coffees. Each person flips a coin. If all the coins come up the same except for one person, then that one person gets to pay for all the coffee. If the coins do not result in this way, then everyone flips again until there

Probability for a Ball Season

Bob Jones of the Alaskan Bears baseball club had the highest batting average in the 2000 Major League Baseball season. His average was .335. So assume the probability of getting a hit is .335 for each time he batted. In a particular game assume he batted three times. a. This is an example of what type of probability? b. Wh

Normal Approximation of the Binomial

See the attached file. According to a recent census, 52.2% of New York residents are male. Suppose a group of 100 New York residents are selected at random. A) What is the mean and standard deviation of the number of male members of the group? B) Use the normal approximation to find the probability that less than half of th