Posted by Musa on .
x and y vary inversely, and y = 3 when x = 6. Find y when x = 9.
A. 2
B. 4.5
C. 12
D. 18

Alegrbra 1 
Reiny,
if x and y vary inversely, then
y = kx, where k is a constant
using the given data
3 = k(6)
k = 1/2
so y = x/2
when x = 9, then y = 9/2 or 4.5
or
use an inverse ratio
x1/y1 = x2/y2
6/3 = 9/y
6y = 27
y = 27/6 = 9/2 = 4.5
9y =