A bord and pillar panel has 24 developed pillars of size \(40\ \text{m} \times 40\ \text{m}\) (centre to centre) under extraction. The following information is given:
Gallery width = \(4\ \text{m}\)
Extraction height = \(3\ \text{m}\)
Extraction ratio during depillaring = 80%
Specific gravity of coal = 1.4
Incubation period = 6 months
Average working days per month = 25
In order to extract the panel within the incubation period, the minimum rate of production, in tonne per day, is . (rounded off to one decimal place)