In mix design the proportion 1 : 2 : 4 means:
1
2 part of cement is mixed with 1 part of sand and 4 part of coarse aggregate
2
1 part of cement is mixed with 4 part of sand and 2 part of coarse aggregate
3
1 part of cement is mixed with 2 part of sand and 4 part of coarse aggregate
4
4 part of cement is mixed with 2 part of sand and 1 part of coarse aggregate