3) Before premiering a blockbuster movie at a theater, test screenings are done beforehand. A small number of selected theaters are chosen geographically throughout the country. Each theater chosen is supposed to be representative of theatergoers in that area. Everyone is interviewed when the movie is over: Identify the type of sampling used in this example:
A) Attempted census
B) Systematic sampling
C) Stratified sampling
D) Cluster sampling

A designed experiment is described. Identify the specified element of the experiment.
4) In clinical trial, 780 participants suffering from high blood pressure were randomly assigned to one of three groups. Over one month period, the first group received a low dosage of an experimental drug the second group received a high dosage of the drug and the third group received a placebo The diastolic blood pressure of each participant was measured at the beginning and at the end of the period and the change in blood pressure was recorded. Identify the levels of the factor.
A) Diastolic blood pressure at the start, diastolic blood pressure at the end
B) The experimental drug
C) Placebo, low dosage, high dosage
D) High blood pressure, low blood pressure

Tell whether the statement is true or false.
5) A person's blood type can be classified as A, B, AB, or O. In this example; "blood type" is the variable while A, B, AB, O constitute the data.
A) True
B) False