The variable z is inversely proportional to x. when x is 6, z has the value 2. what is the value of z . when x = 13
round to at least the thousandths place if needed.

Given that z is inversely proportional to x, then:
z α 1/x
hence;
z=k/x
where:
k is the constant of proportionality; 
when x=6, z=2
therefore;
2=k/6
hence;
k=2*6=12

Therefore:
z=12/x
the value of z when x=13 will be:
z=12/13
the answer is 12/13