Question 47792
a varible z varies jointly with x and the square of y.  if z=5 when x=3 and y=4, find the constant of proportionality, k.

The first sentence means z=kxy^2.
You need to solve for "k" as follows:

5=k*3*5^2
5=k(75)
k=1/15

Cheers,
Stan H.