jan 2-2011

The efficiency of the first machine tool is 20% less than that of the 2nd
one. The first machine tool operated for 5 hours, whereas, the second one
operated for 4 hours and together they machined 4000 work pieces. Find the
number of work-pieces machined by the first machine tool.
Solution:
Efficiency of the two machine tools = 80: 100 = 4: 5
Time ratio of the two machine tools = 5: 4
∴ Work ratio of the two machine tools = 4×5: 5×4 = 20: 20 = 1: 1
Thus both the machine tools produced the same number of workpieces
Viz., 4000/2 = 2000

Alternative:
The second machine operating for 4 hours = first machine operating for 5
hours. Hence the first machine would produce 4000 pieces in 10 hours. In 5
hours it would have produced 2000 pieces.