18.
If 9 engines consume 24metric tonnes of coal, when each is working
8
hours a day, how much coal will be required for 8 engines, each
running
13 hours a day, it being given that 3 engines of former type
consume
as much as 4 engines of latter type?
Answer:
Let 3 engines of former type consume 1
unit in 1 hour.
4 engines of latter type consume
1 unit in 1 hour.
1 engine of former type consumes 1/3
unit in 1 hour.
1 engine of latter type consumes ¼
unit in 1 hour.
Let required consumption of coal be
x units.
Less engines, less coal
consumed.(direct)
More working hours, more coal
consumed(direct)
Less rate of consumption, less coal
consumed (direct)
9:8
8:13 ::
24:x
1/3:1/4
(9*8*(1/3)*x)=(8*13*(1/4)*24)
24x=624
x=26 metric tonnes.
