Given that current age of Jack = 12 years
Given that current age of Sophia = 16 years
Jack says that the relationship between his age and Sophia‘s is proportional
If Jack's age is represented by y and Sophia's age by x then we can write y=kx as they are in proportion
where k is called constant of proportion
Now let's plug given ages of each that is y=12 and x=16 into y=kx to find the constant of proportionality
12=k*16
12/16=k
Which is same as the given value of constant of proportionality.
Hence Jack is right about his statement.
But if you think about practical life situation then age of both will not be in proportion
For example after 1 year Jack's age will be 13 and Sophiy's age will be 17
then constant of proportionality using new values will be 13/17
Clearly 12/16 and 13/17 are not same.
So in practical life, age of both will not in in proportion.