In a level terrain, a vertical orebody of 20 m uniform width is worked by surface mining

Q. In a level terrain, a vertical orebody of 20 m uniform width is worked by surface mining method. The density of the ore is 2.5 tonne/m³. The ultimate pit has a depth of 60 m, width of 20 m at pit bottom, and a pit slope of 45^o. The overall stripping ratio for this condition in m³/tonne is                                                         .

Ans: 1.2-1.2