PA Mining Law - Sections 251-260 (1) Practice test questions for the PA Mine Officials' Exam
Progress Indicator:
 
Question 2 of 16
2. If the return air current of a mine consists of 50,000 cubic feet of air per minute and also contains 0.8% methane, how much air must be added to reduce the methane content to 0.5%?
Choices:
- 30,000 cubic feet
- 60,000 feet
- 90,000 cubic feet
- none of the above
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