List of top Mine Planning Questions on Sampling: Methods, Practices and Interpretation asked in GATE MN

The data obtained from an air sample analysis of an old working in a coal mine are given.
O2 17.15%, CO2 3.40%, CH4 2.20%, and N2 77.25%. 
Considering atmospheric air contains 
O2 20.95%, CO2 0.03%, and N2 79.02%, 
the percentage of blackdamp in the old working, is____.( round off up to 2 decimals)

The combined sound pressure level measured at a point in a production bench due to one dumper and one shovel is 95 dB(A). If the sound pressure level of shovel alone is 90 dB(A), the sound pressure level of the dumper alone, in dB(A), at the same point is_____.(round off up to 2 decimals)

Match the following features with the corresponding symbols

	Feature in mine plan		Symbol
P	shaft	1
Q	staple shaft	2
R	Abandoned shaft	3
S	Abandoned staple shaft	4