A denote the set of all people who were alive in 2010. Let B denote the set of all
real numbers. Let f assign, to each person in A, their weight during the year 2010.
Is f a function? Explain in complete sentences.

Question

A denote the set of all people who were alive in 2010. Let B denote the set of all
real numbers. Let f assign, to each person in A, their weight during the year 2010.
Is f a function? Explain in complete sentences.

pablok777 · Answer

It's a function iff the weight of all person alive remains constant all the year 2010. It's not very likely, so I think it's not a function. 
A counterexample can be:
         The weight of person x1 in May, 2010 is 80.2kg, and in September the weight of x1 is 81 kg, then 
f(x1) = 80.2 
and
f(x1) = 81.0
then f is not a function.
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