Answer:
D
Step-by-step explanation:
Given y varies directly as x and z then the equation relating them is
y = kxz ← k is the constant of variation
To find k use the condition y = [tex]\frac{8}{3}[/tex] when x = 1 and z = 4 , then
[tex]\frac{8}{3}[/tex] = k × 1 × 4 = 4k ( divide both sides by 4 )
[tex]\frac{2}{3}[/tex] = k
y = [tex]\frac{2}{3}[/tex] xz ← equation of variation
When x = 6 and z = 3 , then
y = [tex]\frac{2}{3}[/tex] × 6 × 3 = [tex]\frac{2}{3}[/tex] × 18 = 2 × 6 = 12
