Assume an underground mining cost of $25.5/ton ore for an orebody. assume open pit mining costs at $0.0028/kg ore removal and $0.0035/kg waste removal. determine the stripping ratio for an open operation that results in break-even cost differential between the two mining methods.

Which statement best explains distribution of natural resources? people tend to settle in locations that have the resources they need for survival. some countries have resources that others lack, so trade between countries becomes vital. fossil fuels come from areas that have mountains and other areas that manufacture synthetic gas. areas with natural resources provide a higher standard of living and better quality of life.

Extensive and unusual cold snaps have occurred here recently. is this evidence that global warming is lessening or not occurring? no—although the long-term trend is for warming, short-term weather patterns can still be variable. no—melting of glaciers and ice caps is making the oceans cooler, which can cause cold snaps. yes-- if global warming really were occurring, cold snaps wouldn’t happen. yes—due to global warming, weather patterns should be become less—not more—variable.

The kind of wood most often used in contemporary furniture is