Suppose z varies directly as x and inversely as y^ 2 . If z = 12 when x = 6 and y = 5 , what is z when x = 7 and y = 8 ?

Answer 1

z = kx/y^2

12 = k(6)/(5^2)

12 = k(6/25)

12 * 25/6 = k

k=50

z = 50x/y^2

when x=7 and y=8, z = 50(7)/8^2

= 350/64

= 175/32

= 5 + 15/32