Mixtures and Allegations

Weighted Average = Aw = (n1A1 + n2A2 + n3A3 + … + nmAm)/ (n1 + n2 + n3 + … + nm).

If we consider only two mixtures, then from above, Aw = (n1A1 + n2A2)/ (n1 + n2).
n1/n2 = (A2 – Aw)/(Aw – A1).

 

If we have N amount of something and x amount of it is withdrawn n times, amount of original quantity left = N * (1-x/N) ^n.

If we have M amount of A & B, x units of the mixture is replaced by B only, then amount of A left = (Original amount of A) * (1 - x/M)^n.