Question

Which relation is not a function? A) Input: name of student; Output: GPA B) Input: price of an item; Output: UPC code Eliminate C) Input: name of student; Output: birth month D) Input: next door neighbors; Output: zip code E) Input: name of high school; Output: total number of scholarships awarded

Answer 1

Answer: (B)

Steps:

(A) valid function because a student can only be associated with one GPA

(B) not a function: given a price there may be multiple products and therefore multiple UPC codes

(C) valid function: given a student there is only one possible month value

(D) valid function: if the neighbors are identified uniquely, and live only in one residence, then there is only one zip code for them

(E) valid function: number of scholarships awarded by a given high school is a single value for that entity.