How do we calcuate right Proportion?

[sam_m400]

How to calculate right proportion of mix? for eg in 1:4:8, he is saying 1 bag of cement = 16 bags of sand = 32 part of aggregate.They do always mix one bag, how do we calculate the ratio of other two (Sand and aggregate). I need for 1 bag of cement what is ratio of other two.

[jult]

i bag of cement volume is 35ltr or 0.035Cu.m caluculate accordingly