Sally Wants to Know What Percentage of Canadian University Students

question 50

Multiple Choice

Sally wants to know what percentage of Canadian university students are receiving financial aid their first year in university. Sally attends a small university with a large percentage of students who commute to campus every day. Sally stands outside of the residence dining hall one weekday evening and hands out surveys to every third person entering the hall for dinner. Sally's data will be invalid because ________.

• A)she did not use a representative sample
• B)she did not define her population
• C)she did not use random sampling
• D)she did not do a pilot test of her survey

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Definitions:

Existential Generalization

A logical inference rule stating that if an assertion is true for some member of a domain, then there exists an element in that domain for which the assertion holds.

Universal Generalization

A logical principle stating that what is true of all instances of a certain class can be said to be generally true of that class.

Existential Instantiation

A logical principle allowing for the inference of the existence of an instance of a predicate from a statement asserting the existence of some (possibly unspecified) instance.

Universal Instantiation

A logical rule stating that if something is true for everything in a certain category, it is true for each specific member of that category.