If x varies inversely as y and x = 20 when y = 600, find y when x = 400.

If x varies inversely as y.

∴ xy = k(constant) …(i)

If x = 20 and y = 600

∴xy = 20× 600 = 12000

⇒ k = 12000

When x = 400, then from Eq. (i)

y× 400 = k

⇒ y × 400 = 12000

⇒