A 15 m³ dragline is deployed in an O.B. bench of an O.C. mine. It works for 40 days at the rate of 6 hrs per shift and 3 shifts a day. The cycle time, bucket fill factor, and operating efficiency of the dragline are respectively 50 s, 0.8, and 75%. The total volume of O.B. in m³ handled by the dragline 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