Correct Option (3)
Let M₁ represent the initial number of men and D₁ represent the initial number of days, which is 6k. Let M₂ represent the new number of men and D₂ represent the new number of days, which is 5k.
Assuming the total work (W) remains constant, the relationship between men and days is given by the formula: M₁ × D₁ = M₂ × D₂.
Substituting the given values:
M₁ × 6k = M₂ × 5k
To determine the new number of men (M₂):
M₂ = 5kM1×6k
M₂ = 56M1
The increase in the number of men is calculated as M₂ - M₁:
Increase = 56M1−M1=5M1
The percentage increase is determined by dividing the increase in men by the initial number of men and multiplying by 100:
Percentage Increase = M15M1×100=51×100=20%
Therefore, the number of men should be increased by 20% to complete the work in 5k days.
Incorrect Options:
Options 1 (10%), 2 (350%), and 4 (25%) are incorrect. These values do not correspond to the calculated percentage increase derived from the inverse proportionality between the number of men and the time required to complete a fixed amount of work.