Answer:
• k=2.4
,• z=114998.4
Explanation:
If z varies jointly with the cube of x and the square of y, then we have:
[tex]\begin{gathered} z=kx^3y^2 \\ k=\text{constant of proportionality} \end{gathered}[/tex]If z = 76.8 when y = 2 and x = 2:
[tex]\begin{gathered} 76.8=k\times2^3\times2^2 \\ 76.8=k\times8\times4 \\ 32k=76.8 \\ k=\frac{76.8}{32} \\ k=2.4 \end{gathered}[/tex]Next, we write an equation for z in terms of x and y:
[tex]z=2.4x^3y^2[/tex]Finally, when y=6 and x=11:
[tex]\begin{gathered} z=2.4\times11^3\times6^2 \\ z=114998.4 \end{gathered}[/tex]