Final answer:
The equation of variation where y varies jointly as x and the square of z is y = 0.456xz^2.
Step-by-step explanation:
The equation of variation where y varies jointly as x and the square of z can be written as:
y = kxz^2
To find the value of k, we can use the given information in the question. When x=55 and z=3, y=231.
Substituting these values into the equation, we get:
231 = k * 55 * 3^2
Simplifying the equation, we find:
k = 231 / (55 * 9) = 0.456
Therefore, the equation of variation is y = 0.456xz^2.