please help Fill in the blank with the appropriate problem n

Fill in the blank with the appropriate problem number (18, 19, or 20) and then give the solution (you may use scientific notation, rounded to the nearest tenth, if necessary). Problem 21 can be solved with the setup given in problem_. and the solution to problem 21 is: Problem 22 can be solved with the setup given in problem_. and the solution to problem 22 is: Problem 23 can be solved with the setup given in problem_. and the solution to problem 23 is: Circle the most appropriate description. A city planning committee surveys 100 people waiting at a bus stop about the expansion of the public transportation system. random sample systematic sample self-selected sample convenience sample bipartisan sample stratified random sample Volunteers stop to survey residents at every fourth house from the end of each block in town. random sample systematic sample self-selected sample convenience sample bipartisan sample stratified random sample Do you agree that the cafeteria should serve ice cream in various tasty flavors? potentially biased question not potentially biased question

Solution

27)

Obtaining a genuine random sample is difficult. We usually use Random Number Tables, and use the following procedure;

answer is a) random sample.

28)

Systematic Sample

With this method, items are chosen from the population according to a fixed rule, e.g. every 10^th house along a street. This method should yield a more representative sample than the random sample (especially if the sample size is small). It seeks to eliminate sources of bias, e.g. an inspector checking sweets on a conveyor belt might unconsciously favour red sweets. However, a systematic method can also introduce bias, e.g. the period chosen might coincide with the period of faulty machine, thus yielding an unrepresentative number of faulty sweets.

answer is systematic sample.

29)

BIASED SAMPLES

A sample chosen for a survey should be representative of the population. A biased sample is a sample that is not representative. In a biased sample, parts of the population may be over-represented or under-represented

answer is potentiallyt biased sample