Mining

Title: Comparison of Costs
Type: Table
Date: 1931
Source: Minnesota Historical Society

Description: This table presents data on the costs of mining in open pit and underground mines.

Activities:

1. Has the amount of ore that's been mined gone up every year?
   
   
   
   
   Answer: The "tonnage mined" column shows that in 1927 the amount went down, but then it went back up again for both open-pit and underground mining by 1929.
2. Approximately how much more total ore was mined open-pit than underground?
   
   
   
   
   Answer: More than three times as much ore was mined using the open-pit method—about 90 million more tons. The actual difference is 126,478,819 - 37,113,134, or 89,365,685 tons.
3. During the four years shown, was the "total average cost per ton" ever cheaper for underground mining than it was for open-pit?
   
   
   
   
   Answer: No, it wasn't, although every year in the table the two costs got a little closer to each other.
4. According to the "total average cost per ton" column of the table, about how much more expensive was underground mining than open-pit mining?
   
   
   
   
   Answer: Underground mining is about twice as expensive.