The beginning of the amazing events at Krakatoa in 1883 date to May 20 when there were initial rumblings and venting from the volcano, which had been dormant for about 200 years.
A refinery margin is the revenue associated with refining petroleum, expressed as a value per volume (e.g. $/L), net of the cost of the crude oil input. The simplest refining
A: Operating margin and profit margin both measure the efficiency of a firm by comparing profits against costs at three different spots on an income statement. On their own, these margins do not tell much of a story, but they are very useful when compared to past periods or to competitor firms in the same industry.