y varies jointly as x and z, and y=98/3 when x=2 ans z=7. Find y when x=7 and z=3.

Question

Options:

A: y=7/3xz; 49
B: y=6/7xz; 18
C: y=14/3xz; 98
D: y=3/7xz; 9

Answer 1

Let
y=kxz
98/3=k(2*7)
k=98/3/14=7/3
Therefore y=(7/3)xz
when x=7, z=3
then y=(7/3)*7*3=49