9 engines consume 24 metric tonnes of coal, when each is working 8 hours day. How much coal is required for 8 engines, each running 13 hours a day, if 3 engines of former type consume as much as 4 engines of latter type?	Choose the correct choice from the following choices.
A) 20 metric tonnes
B) 22 metric tonnes
C) 24 metric tonnes
D) 26 metric tonnes
E) 28 metric tonnes
Explanation:   Let required amount of coal be x metric tones   More engines, more amount of coal (direct proportion)   If 3 engines of first type consume 1 unit, then 1 engine will consume 13 unit which is it’s the rate of consumption.   If 4 engines of second type consume 1 unit, then 1 engine will consume 14 unit which is it’s the rate of consumption   More rate of consumption, more amount of coal (direct proportion)   More hours, more amount of coal(direct proportion)   Hence we can write as   (engines) 9:8   (consumption rate )13:14   (hours) 8:13::24}::x   ⇒9×1/3×8×x=8×1/4×13×24   ⇒3×8×x=8×6×13   ⇒3×x=6×13   ⇒x=2×13=26   Answer: Option 26 metric tonnes
<result>D</result>
9 engines consume 24 metric tonnes of coal, when each is working 8 hours day. How much coal is required for 8 engines, each running 13 hours a day, if 3 engines of former type consume as much as 4 engines of latter type?