A mining company operates a large heap-leach gold mine in the western United States. The gold mined at this location consists of ore that is very low grade, having about 0.0032 ounce of gold in 1 ton of ore. The process of heap-leaching involves the mining, crushing, stacking, and leaching millions of tons of gold ore per year. In the process, ore is placed in a large heap on an impermeable pad. A weak chemical solution is sprinkled over the heap and is collected at the bottom after percolating through the ore. As the solution percolates through the ore, the gold is dissolved and is later recovered from the solution. This technology, which has been used for more than 30 years, has made the operation profitable. Due to the large amount of ore that is handled, the company is continually exploring ways to improve the process. As part of an expansion several years ago, the stacking process was automated with the construction of a computer controlled stacker. This stacker was designed to load 35,000 tons of ore per day at a cost that was less than the previous process that used manually operated trucks and bulldozers. However, since its installation, the stacker has not been able to achieve these results consistently. Data for a recent 35-day period that indicate the amount stacked (tons) and the downtime (minutes) are stored in the file Mining. Other data that indicate the causes for the downtime are stored in Mining2.
Analyze the data, making sure to present conclusions about the daily amount stacked and the causes of the downtime. In addition, be sure to develop a model to predict the amount stacked based on downtime.