we know that
A relationship between two variables, x, and y, represent a proportional variation if it can be expressed in the form y=kx
where
k is the constant of proportionality
Verify each table
table a
Let
x ----> distance
y ----> sound level
For each ordered pair calculate the value of k
k=y/x
so
(5,85) -----> k=85/5=17
(10,79) ----> k=79/10=7.9
the values of k are differents
that means
the table nor represent a proportional relationship
table b
let
x ----> volume
y ----> cost
k=y/x
(16,1.49) ----> k=1.49/16=0.093125
(20,1.59) ----> k=1.59/20=0.0795
the values of k are differents
that means
the table nor represent a proportional relationship