Consider the following function definition.

Domain: The set of months {January, February, ..., December} .
Codomain: All integers in the range [1, 31] .
Rule: f(month) = number of days in that month in 2025

Which of these statements is true with respect to this function?

Question

Consider the following function definition. 
 
 Domain:  The set of months  {January, February, ..., December} . 
 Codomain:  All integers in the range  [1, 31] . 
 Rule:   f(month) = number of days in that month in 2025 
 
 Which of these statements is true with respect to this function?

Answer

The image is a proper subset of the codomain.

Answer

Restricting the codomain to  {30,31}  would still give you a valid function.

Answer

It is a surjection.

Answer

Restricting the codomain to  {28, 29, 30, 31}  would make the function a surjection.

Crowdly

Consider the following function definition. Domain: The set of months {Jan...

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