Hi! We're making a Design of Experiment that involves the use of rubber band and egg shell to see of it affect compression strength of a concrete.
So, we make a proportion of the cement and two control variables in interval like
1. 100:0:0
2. 50: 50 :0
3. 50: 0: 50
4. 50: 25: 25
5. 50: 75...