If 9 engines consume 24 metric tonnes of coal, when each is working 8 hoursa day, how much coal will be required for 8 engines, each running 13 hours a day, it is being given that 3 engines of former type consume as much as 4 engines of latter type?  Options.
A) 23	B) 25	C) 26	D) 28	E) 30

Rationale: explanation : let 3 engines of former type consume 1 unit in 1 hour . then , 4 engines of latter type consume 1 unit in 1 hour . therefore 1 engine of former type consumes ( 1 / 3 ) unit in 1 hour . 1 engine of latter type consumes ( 1 / 4 ) unit in 1 hour . let the required consumption of coal be x units . less engines , less coal consumed ( direct proportion ) more working hours , more coal consumed ( direct proportion ) less rate of consumption , less coal consumed ( direct proportion ) number of engines 9 : 8 working hours 8 : 13 } : : 24 : x rate of consumption ( 1 / 3 ) : ( 1 / 4 ) ( 9 * 8 * ( 1 / 3 ) * x ) = ( 8 * 13 * ( 1 / 4 ) * 24 ) < = > 24 x = 624 < = > x = 26 . answer : c
Answer: C