Question

Z varies inversely with the product of x and y. When x = 2 and y = 4, z = 0.5

What is the value of z when x = 4 and y = 9?

Answer 1

Hello,
z=k/(xy), if x=2 and y=4 then z=1/2
==>1/2=k/(2*4)==>k=8*2==>k=4

Answer 2

We represent this indirect variation by,
z = k/xy
where k is the constant of the variation.
Substituting the first set of values for the variables,
0.5 = k/(2 x 4) ; k = 4
Now for the second set,
z = 4/(4 x 9) ; z = 1/9
Thus, the value of z is 1/9.