Question

Let h be the function that assigns each student ID number to a grade level.

h:{student ID number} → {grade level}
Assign each student ID number to the student’s current grade level.
c. Jonny says, "This is not a function because every ninth grader is assigned the same range value of 9. The range
only has 4 numbers {9, 10, 11, 12}, but the domain has a number for every student in our school." Explain to
Jonny why he is incorrect.

Answer 1

It is a function Jonny!

Explanation:

Hello! I would say to Jonny:

Jonny! A function is a relation between two sets, in which every element of the first set (domain) is assigned only one element of the second set (codomain).

If you have serveral elements of the first set with the same corresponding element of the second set it is correct to call that relation a function.

However, if you have an element of the first set for which your relation can relate to more than one element of the second set, then Jonny, that is not a function.

In the present case, every student ID number can only be realted to a number of the set {9, 10, 11, 12}, a student cannot have more than one current grade level. Therefore, that relation is in fact a function