Question

If $ is jointly proportional to the cube of y and fourth power of z , in what ratio is s increased or decreased when y halved and z is doubled?

Answer 1

s(y,z) = ky^3z^4

so,
s(y/2,2z) = k(y/2)^3 * (2z)^4 = k * y^3/2^3 * 2^4 * z^4 = 2s(y,z)