In a mine deploying shovel and dumper, the distance from the crest of the bench to the centre of the dumper including safety berm and clearance is 7.5m, the dumping radius and the cutting radii of the shovel are 15m and 12m respectively. The width of the working bench of the mine in m is

When the occurrence of mineral (e.g. rare minerals) is randomly distributed in a rock then which of the distribution pattern is statistically followed?

A. Normal distribution

B. Skewed distribution

C. Lognormal distribution

D. Poisson distribution

Which of the following combination of SDL based mining is expected to give best production and productivity of SDL?

A. 3 level heading district

B. 4 level heading district

C. 5 level heading district

D. 6 level heading district

It is very difficult to control shaley roof if coal is not left with the shale why?

A. It is weak in nature

B. It has weathering effect

C. It has great affinity to absorb moisture and get departed from immediate roof

D. It reacts with coaly surface

In connection with lowering or raising of persons by means of bucket etc. for a shaft exceeding "A" m in depth, there shall be significant cover overhead for protection from things falling down the shaft. A is given by

A. 130m

B. 190m

C. 270m

D. 500m