Assume Gold is at $1229 an ounce and Silver at $16.98 an ounce in the international market. How much should the ideal MCX price be?

There is always a difference if I multiply the USDINR rate and try to calculate. So I am assuming there is more to it than just multiplying the USDINR rate with the Gold/Silver $ rate.

Any fixed formula to calculate this parity/disparity.