Question

he variable z is directly proportional to x, and inversely proportional to y. When x is 7 and y is 7, z has the value 2. What is the value of z when x=10, and y=12?

Answer 1

$z \alpha \frac{x}{y}$
$z = \frac{kx}{y}$
Case 1:
But, x=7, y=7 and z=2
From;
$z = \frac{kx}{y}$
$2 = \frac{k7}{7}$
$2 \times 7 = 7k$
$14 = 7k$
$k = \frac{14}{7}$
$k = 2$
Therefore;
From;
$z = \frac{kx}{y}$
$z = \frac{2x}{y}$
Case 2:
z=?, x=10, y=12
From;
$z = \frac{2x}{y}$
$z = \frac{2(10)}{12}$
$z = \frac{20}{12}$
Therefore;
$z = \frac{5}{3}$