Exam 7: Sampling and Sampling Distributions

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.What is the probability that the sample mean will be greater than 100 grams?

The evening host of a dinner dance reached into a bowl,mixed all the tickets around,and selected the ticket to award the grand door prize.What sampling method was used?

The standard error of the mean

TABLE 7-7 Online customer service is a key element to successful online retailing.According to a marketing survey,37.5% of online customers take advantage of the online customer service.Random samples of 200 customers are selected. -Referring to Table 7-7,the standard error of all possible sample proportions is ________.

As the size of the sample is increased,the standard deviation of the sampling distribution of the sample mean for a normally distributed population will stay the same.

The Central Limit Theorem is considered powerful in statistics because it works for any population distribution provided the sample size is sufficiently large and the population mean and standard deviation are known.

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.What is the probability that the sample mean will be between 39 and 48 minutes?

There can be only one sample selected from a population.

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 7-5,90% of the samples will have more than what percentage of customers who will make a purchase after visiting the website?

The owner of a fish market has an assistant who has determined that the weights of catfish are normally distributed,with mean of 3.2 pounds and standard deviation of 0.8 pound.If a sample of 25 fish yields a mean of 3.6 pounds,what is the Z-score for this observation?

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 it is assumed that the amount of gasoline purchased per car is symmetric,there is approximately a 68.26% chance that a random sample of 16 cars will have a sample mean between 14 and 16 gallons.

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?

To use the normal distribution to approximate the binomial distribution,we need ________ and ________ to be at least 5.

A sampling distribution is a distribution for a statistic.

The standard error of the sampling distribution of a sample proportion is where ρ is the sample proportion.

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 less than ________ % who have high-speed access to the Internet.

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.What is the probability that the sample mean will be between 100 and 120 grams?

TABLE 7-7 Online customer service is a key element to successful online retailing.According to a marketing survey,37.5% of online customers take advantage of the online customer service.Random samples of 200 customers are selected. -Referring to Table 7-7,________ % of the samples are likely to have between 35% and 40% who take advantage of online customer service.

Measurement error can become an ethical issue when an interviewer purposely guides the responses in a particular direction.

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,the requirements for using a normal distribution to approximate a binomial distribution is fulfilled.