Question

In each of the following problems:

What is the sample being studied.

State what constitutes the population.

Identify at least one variable.

Determine if the variable is quantitative or qualitative.

Determine if the variable is continuous or discrete (for quantitative) or nominal or ordinal (for qualitative).

Find a statistic in the scenario.

Find a parameter in the scenario.

Determine the type of sampling method used.

The newly starting online company wants to better predict the monthly online sales of its product. Last month the company received 560 online orders. The CEO randomly selected 120 of the received orders by using the RAND function in Excel. The mean sales of the 120 orders was $640. It was determined that the average sales for all orders last month was $710.

Movie-At-Home sends movies to subscriber homes based on the requests of the subscribing customer. The quality manager desires to improve the defective return rate of the movies. To ensure the quality standard is met, the manager decides to test the number of defective movies being sent out to the customers. At the beginning of the study the manager picks a random number between 1 and 12 representing the number of hours that movies are sent out from the facility each day of the week. If the random number 5 is selected, then at the beginning of the 5^th hour of operation each day until the desired sample size is attained, one movie is selected for quality testing. The selected movie each day will be played to determine if it meets quality standards. The current defective return rate for all movies is less than 1%. The quality manager is pleased to see that less than .5% of the sample are defective therefore meeting quality standards.

The Gallup organization is conducting a telephone survey to determine how respondents view their physical health in a major city. The city is divided according to the squares on a transportation road map. They take a simple random sample of the squares on the map. For each square chosen they call each household in the square and ask the question on the survey. A total of 560 surveys are completed. The question asked in the survey is “How would you describe your physical health?” The possible responses are Excellent, Good, Fair, Poor, or No Opinion. In analyzing the results, the organization concluded that 65% of the homes sampled stated Excellent describing their current health. A past study completed in 2008 found that less than 35% of all homes in this major city had this same opinion of being in Excellent health.

A hospital is trying to improve its patient services. The hospital administrator randomly chooses one nurse from each floor of the hospital to serve on a fact committee. The nurses are asked to keep track of how many patients they visit during each hour of the day on the nurses' daytime shifts. At the end of a month the administrator collects the information and concludes that the nurses see an average of 22 patients per hour. Based on this information the administrator reports that the average number of patients visited per hour by all nurses is 20.

A group of financially concerned college seniors at a particular college wanted to see how much students could save on text books by renting or using an e-book versus buying a hard copy text book. Each of the 5 members of the group chooses 10 of their classmates and asks them how much money they would have saved by renting or using an e-book versus purchasing hard copy text books for all of their courses last term. The group found that the mean amount these 50 people saved was $250 for the term. The result of the study concluded that all students at this college saved an average of $275 last term.

Answer 1

Sample: CEO who selects 120 online orders at random to find the average sales will constitutes sample. Here n =120

Population: Total number of orders received by the company in the last month will constitues population. The number of units in the population is called Population size, denoted by N. Here N = 560 online orders.

Random variable: X : Sale of the Online company by its oders.

Continuous or Discrete: In this problem, Random variable is Continuous random variable. Because the sale of an order may takes intergers or fractions.

Statistic: Any sample charecterstic is called Statistic. Here   is the sample mean. i.e., the average sales from the sample of 120 online orders

Parameter: Any Population charecterstic is called Parameter. Here is called Population parameter. i.e., Average sales of from the whole 560 online orders.

Type of sampling method: As the online company selects the sample from the population at random without having any bias or favour or pre determined criteria, this kind of sampling is called Simple random sampling. in Simple random sampling each unit of the population has an equal chance to be selected into the population.

Thank you