Which one is a function? a or b?

Set A contains zip codes from the US and set B contains US citizen's social security numbers. The elements of these sets can be paired in that each person has a zip code for their legal address (or domicile) and eachperson has a social security number.

(a) If these are written as ordered pairs of the form (zip code; Social security number) do we have a function? Why or why not?

(b) If these are written as ordered pairs of the form (Social security number; zip code) do we have a function? Why or why not?

Question

Which one is a function? a or b? 

Set A contains zip codes from the US and set B contains US citizen's social security numbers. The elements of these sets can be paired in that each person has a zip code for their legal address (or domicile) and eachperson has a social security number. 

(a) If these are written as ordered pairs of the form (zip code; Social security number) do we have a function? Why or why not? 

(b) If these are written as ordered pairs of the form (Social security number; zip code) do we have a function? Why or why not?

campbell_st · Answer

you have a function as each unique social security number maps to a zip code... 

the reverse is not a function.