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MATH225 Week 1 Assignment : Comparing Sampling Methods
(Q & A)
1. A television station plans to send a crew to a polling center on an election day. Because they do not have time to interview each individual voter, they decide to count voters leaving the polling location and ask
every 20 th voter for an interview. What type of sampling is this?
Select the correct answer below: Simple random sampling Cluster sampling Stratified Sampling Systematic sampling Convenience sampling
2. In order to study the shoe sizes of people in his town, Billy samples the population by dividing the residents by age and randomly selecting a proportionate number of residents from each age group. Which type of sampling is used? Select the correct answer below: Systematic sampling Stratified sampling Convenience sampling Cluster sampling 3. The management of a large airline wants to estimate the average time after takeoff taken before the crew begins serving snacks and beverages on their flights. Assuming that management has easy access to all of the information that would be required to select flights by each proposed method, which of the following would be reasonable methods of stratified sampling? Select all that apply.
For each day of the week, randomly select 5% of all flights that depart on that day of the week.
Divide all flights into the following 4 groups on the basis of scheduled departure time: before 9 : 00 am, 9 : 00 am
o 1 : 00 pm, 1 : 00 pm to 5 : 00 pm, and after 5 : 00 pm. Randomly select 5% of the flights in each group.
For each crew member the airline employs, randomly select 5 flights that the crew member works.
Divide the airports from which the airline's flights depart into 4 regions: Northeast, Northwest, Southwest, and
Southeast. Randomly select 5% of all flights departing from airports in each region.
4. To study the mean respiratory rate of all people in his state, Frank samples the population by dividing the
residents by towns and randomly selecting 12 of the towns. He then collects data from all the residents in
the selected towns. Which type of sampling is used? Select the correct answer below: Convenience sampling Systematic sampling Stratified sampling Cluster sampling
5. When is stratified sampling appropriate? Select the correct answer below: Stratified sampling is a good choice when the population has multiple distinct groups that are each likely to be representative of the population as a whole. Stratified sampling is a good choice when the population has multiple distinct groups that are internally homogenous but not representative of the population as a whole. Stratified sampling is a useful method if the population is not well understood or there are no groups within the population that need to be analyzed individually. Stratified sampling is a useful method when the individuals in the population are generated in a continuous stream, like on an assembly line. 6. In reference to different sampling methods, cluster sampling includes the steps: use simple random sampling to select a set of groups; every individual in the chosen groups is included in the sample.
Obtain a convenience sample by visiting the 100 restaurants that are closest to the executive's office. Obtain a systematic sample by selecting every 20 th restaurant from a list that orders all restaurants by date of opening. Obtain a stratified sample by visiting 1 randomly selected restaurant in every county. Obtain a cluster sample by randomly selecting 20 counties and visiting every restaurant within those counties.
10. In order to study the wrist sizes of people in her town, Kathryn samples the population by dividing the residents by age and randomly selecting a proportionate number of residents from each age group. Which type of sampling is used? Select the correct answer below: Cluster sampling Convenience sampling Stratified sampling Systematic sampling
11. A manufacturer has three tool centers that each make about 1000 tools every day. In order to implement
better quality-control procedures, the manager wants to start sampling the tools made each day to be able to identify issues as quickly as possible. Which sampling method would be most appropriate? Select the correct answer below: At the end of each day, select a random sample of 60 tools from all the tools produced that day. At the end of each day, select random samples of 20 tools from the tools produced by each tool center that day. Select the first 20 tools produced by each tool center on each day. Select every 50 th tool produced by each tool center during the day. Select every 150 th tool produced by any tool center during the day.
12. To study the mean blood pressure of all people in her state, Christine samples the population by dividing
the residents by towns and randomly selecting 9 of the towns. She then collects data from all the residents
in the selected towns. Which type of sampling is used? Select the correct answer below:
Convenience sampling Systematic sampling Cluster sampling Stratified sampling
13. When is using a simple random sample appropriate? Select the correct answer below: A simple random sample should always be used if possible. A simple random sample should be used if the population is not well understood or there are no groups within the population that need to be analyzed individually. A simple random sample should be used when the population has well-defined groups that are relatively homogeneous. This will make sure each group is represented proportionally.
- Donald is studying the eating habits of all students attending his school. He samples the population by dividing the students into groups by grade level and randomly selecting a proportionate number of students from each group. He then collects data from the sample. Which type of sampling is used? Great work! That's correct. Systematic sampling Convenience sampling Stratified sampling Cluster sampling
15. A grocer receives cartons of 12 eggs in boxes of 100 cartons. In a particular month, the grocer
receives 4 shipments of eggs with 20 boxes in each shipment. The grocer wants to estimate the proportion
of cartons he receives this month that include at least one broken egg. Which of the following sampling methods would be most appropriate? Select the correct answer below: Obtain a stratified sample by examining 100 randomly selected cartons from each of the 4 shipments. Obtain a cluster sample by randomly selecting 3 boxes and examining every carton in those 3 boxes.
