Tables and Frequency Tables: แบบฝึกหัด

A student wants to investigate the average height of all 800 students in a school. She decides to measure the heights of every 10th student on the alphabetical student list. Identify the sampling method used.

A quality control manager wants to check the quality of light bulbs produced in a factory. He inspects the first 10 light bulbs produced every hour. Which sampling method is being used?

A library manager wants to conduct a survey about the reading habits of the library's members. The manager divides the members into different age groups: children, teenagers, adults, and seniors. Then, 50 members are randomly selected from each age group for the survey. Which of the following sampling methods is being used?

A researcher selects every 50th name from a local telephone directory to conduct a survey. Which sampling method is being used?

A school principal wants to understand the opinions of students regarding the new cafeteria menu. She puts the names of all 1,200 students in a box, shakes it, and draws 100 names. Identify the sampling method used.

A researcher wants to study the eating habits of students in a school with 1000 students by interviewing every 20th student on the school register. Identify the sampling method used.

A school principal wants to investigate the average time spent on homework by 1,200 students in the school.

(a) The principal decides to select the first 50 students who enter the school library on a Monday morning as the sample. Identify this sampling method and explain why it might lead to a biased result.
(b) Suggest a more appropriate probability sampling method to ensure every student has an equal chance of being selected, and briefly describe the steps to implement it.
(c) If the principal wants to ensure that the sample reflects the distribution of students across the six different grade levels (Secondary 1 to Secondary 6), identify the most suitable sampling method and calculate the number of students to be selected from Secondary 4 if the total sample size is 150 and there are 184 students in Secondary 4.