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If the true discount on a certain sum due some time hence be ₹35, the sum being ₹560, find the rate percent:
280 days
35 days
140 days
70 days
70 days
Convert the men and women into a single unit of work efficiency, equate the two total work expressions to find the efficiency ratio between a man and a woman, then calculate total work and divide by the combined efficiency of 1 man and 2 women.
8 men and 12 women can build a wall in 10 days, 6 men and 8 women can build the same wall in 14 days
Total Work=Efficiency×Time
Convert the men and women into a single unit of work efficiency, equate the two total work expressions to find the efficiency ratio between a man and a woman, then calculate total work and divide by the combined efficiency of 1 man and 2 women.
Confusing the individual daily work rate of men versus women by adding their counts directly without determining their relative efficiencies first.
Step 1: Set up the total work equations
Let the daily efficiency of one man be M and one woman be W. Equating the total work from both conditions: (8M+12W)×10=(6M+8W)×14
(8M+12W)×10=(6M+8W)×14
Step 2: Find the efficiency ratio between men and women
Expanding and simplifying the equation: 80M+120W=84M+112W⟹4M=8W⟹M=2W This shows a man is twice as efficient as a woman (M/W=2/1).
M=2W
Step 3: Calculate the total work in units
Substitute M=2W into the first equation to find total work: Total Work=(8(2W)+12W)×10=(16W+12W)×10=280W
Total Work=280W
Step 4: Calculate time taken by 1 man and 2 women
Combined efficiency of 1 man and 2 women is 1M+2W=1(2W)+2W=4W. Time required is: Time=4W280W=70 days
Time=70 days
D is correct because 2 women and 1 man together take 70 days to build the wall.
This method of converting mixed worker efficiencies into a unified unit scale is identical to solving pipe and cistern problems involving different flow rates.