Extracted text: 6. A rectangular 12m x 9m coal pillar is located 100m below surface. Panel road widths are 7m, mining height is 2.5m. Panel encounters a dolerite sill and the load increases by 15%. i. Calculate the load and safety of the pillar. ii. Calculate the thickness of the dolerite sill and new safety factor. iii. Discuss the controllable parameter/s in regards to enhancing the stability of the beam in the roof.