Question

Z varies jointly as x and y. z=60 when x=5 and y=6. find z when x = 7 and y=3

Answer 1

z = 42

Explanation:

The question can be answered in 2 steps as follows:

Step 1: Calculation of the constant of the variation

The equation for the joint variation can be given as follows:

z = cxy ................... (1)

Where;

z = 60

c = constant = ?

x = 5

y = 6

Substituting the values into equation (1) and solve c, we have:

60 = c * 5 * 6

60 = c * 30

c = 60 / 30

c = 2

Step 2: find z when x = 7 and y = 3

Since from Step 1 c = 2, we now use equation (1) and substitute the values into it to find z as follows:

z = 2 * 7 * 3

z = 42