Question

y varies jointly with p and q. When p = 12 and q = 4, y = 144. Find y when p = 10 and q = 6.

Answer 1

p = 12, q = 4, y = 144.
y = kpq,
y = k*12*4 = 144,
k*12*4 = 144,
48k = 144,
k = 144/48 = 3.

Check: y = 3*12*4 = 144.


p=10, q = 6.

y = kpq = 3 * 10 * 6 = 180.