Find the conversion value of a convertible preferred stock that carries a conversion ratio of 1.8, given that the market price of the underlying common stock is $40 a share. Would there be any conversion premium if the convertible preferred were selling at $90 a share? If so, how much (in dollar and percentage terms)? Also, explain the concept of conversion parity, and then find the conversion parity of this issue, given that the preferred trades at $90 per share.