Q. Suppose that z varies jointly with the cube of x and the square of y. Find the constant of proportionality k if z=3600 when y=3 and x=5.
Identify general form: Identify the general form of joint variation.Joint variation is expressed as z=k×xn×ym, where k is the constant of proportionality, and n and m are the powers to which x and y are raised, respectively. In this case, since z varies jointly with the cube of x and the square of y, the equation becomes z=k×x3×y2.
Substitute values into equation: Substitute z=3600, y=3, and x=5 into the joint variation equation z=k×x3×y2.3600=k×53×32
Calculate x3 and y2: Calculate the values of x3 and y2.53=5×5×5=12532=3×3=9
Substitute calculated values: Substitute the calculated values into the equation. 3600=k×125×9
Solve for constant of proportionality: Solve the equation for the constant of proportionality, k.3600=k×(125×9)3600=k×1125k=11253600
Perform division: Perform the division to find the value of k.k=11253600k=3.2
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