Exam 7: Sampling and Sampling Distributions

The Central Limit Theorem ensures that the sampling distribution of the sample mean approaches a normal distribution as the sample size increases.

TABLE 7-6 According to an article, 19% of the entire population in a developing country have high-speed access to the Internet. Random samples of size 200 are selected from the country's population. -Referring to Table 7-6, among all the random samples of size 200, 90 % will have more than ________ % who have high-speed access to the Internet.

TABLE 7-1 The manager of the customer service division of a major consumer electronics company is interested in determining whether the customers who have purchased a DVD player made by the company over the past 12 months are satisfied with their products. -Referring to Table 7-1, if there are 4 different brands of DVD players made by the company, the best sampling strategy would be to use a

TABLE 7-5 According to a survey, only 15% of customers who visited the website of a major retail store made a purchase. Random samples of size 50 are selected. -A study at a college in the west coast reveals that, historically, 45% of the students are minority students. If a random sample of size 75 is selected, the probability is ________ that more than half of the students in the sample will be minority students.

TABLE 7-6 According to an article, 19% of the entire population in a developing country have high-speed access to the Internet. Random samples of size 200 are selected from the country's population. -Referring to Table 7-6, among all the random samples of size 200, ________ % will have between 14% and 24% who have high-speed access to the Internet.

TABLE 7-2 The time spent studying by students in the week before final exams follows a normal distribution with a standard deviation of 8 hours. A random sample of 4 students was taken in order to estimate the mean study time for the population of all students. -Referring to Table 7-2, what is the probability that the sample mean exceeds the population mean by more than 2 hours?

TABLE 7-5 According to a survey, only 15% of customers who visited the website of a major retail store made a purchase. Random samples of size 50 are selected. -A study at a college in the west coast reveals that, historically, 45% of the students are minority students. If random samples of size 75 are selected, the standard error of the proportion of students in the samples who are minority students is ________.

TABLE 7-5 According to a survey, only 15% of customers who visited the website of a major retail store made a purchase. Random samples of size 50 are selected. -Referring to Table 7-5, what is the probability that a random sample of 50 will have at least 30% of customers who will make a purchase after visiting the website?

The average score of all pro golfers for a particular course has a mean of 70 and a standard deviation of 3.0. Suppose 36 pro golfers played the course today. Find the probability that the average score of the 36 pro golfers exceeded 71.

________ results from the exclusion of certain groups of subjects from a population frame.

TABLE 7-5 According to a survey, only 15% of customers who visited the website of a major retail store made a purchase. Random samples of size 50 are selected. -A study at a college in the west coast reveals that, historically, 45% of the students are minority students. If random samples of size 75 are selected, 95% of the samples will have more than ________ % of minority students.

Systematic samples are less efficient than a stratified sample.

Assume that house prices in a neighborhood are normally distributed with a standard deviation of $20,000. A random sample of 16 observations is taken. What is the probability that the sample mean differs from the population mean by more than $5,000?

A company selling apparel online sends out emails every Monday to all its customers who made a purchase. This is an example of a

The amount of time required for an oil and filter change on an automobile is normally distributed with a mean of 45 minutes and a standard deviation of 10 minutes. A random sample of 16 cars is selected. 95% of all sample means will fall between what two values?

Suppose the ages of students in Statistics 101 follow a right skewed distribution with a mean of 23 years and a standard deviation of 3 years. If we randomly sampled 100 students, which of the following statements about the sampling distribution of the sample mean age is incorrect?

The question "Is your household income last year somewhere between $50,000 and $100,000?" will most likely result in coverage error.

The amount of tea leaves in a can from a particular production line is normally distributed with μ = 110 grams and σ = 25 grams. A sample of 25 cans is to be selected. So, the middle 70% of all sample means will fall between what two values?

If the amount of gasoline purchased per car at a large service station has a population mean of 15 gallons and a population standard deviation of 4 gallons and a random sample of 4 cars is selected, there is approximately a 68.26% chance that the sample mean will be between 13 and 17 gallons.

Major league baseball salaries averaged $3.26 million with a standard deviation of $1.2 million in a recent year. Suppose a sample of 100 major league players was taken. Find the approximate probability that the mean salary of the 100 players was less than $2.5 million.