Q. Certain no. of men can finish a piece of work in 10 days. If however there were 10 men less it will take 10 days more for the work to be finished. How many men were there originally.

• 110
• 14 years agoHelpfull: Yes(6) No(4)
• let there be x men initially.....considering their physical strength of all constant.....
  then 1 men can finish work in 1 day = (1/10x) th of total.
  when 10 men were less
  then 1 men can finish work in 1 day = (1/(x-10)*20) th of total
  equating the both
  10x=(x-10)*20
  we get
  x=20
  so initially there were 20 men
  
• 14 years agoHelpfull: Yes(4) No(2)
• 20 men
• 14 years agoHelpfull: Yes(3) No(2)
• 20
• 14 years agoHelpfull: Yes(2) No(2)
• 20 men were there originally
• 14 years agoHelpfull: Yes(2) No(2)
• 20 men.
• 14 years agoHelpfull: Yes(2) No(2)
• 20
• 14 years agoHelpfull: Yes(2) No(3)
• This involves an application of indirect/inverse proportionality. An indirect/inverse relation exists when, between two variables, an increase in the value of the first one causes the other to decrease, and vice-versa.
  
  In the problem you gave, number of days, and the number of men vary indirectly/inversely. This means, that the more men you have working (increasing the number of men), will let them finish the work in less days (decreasing the number of days).
  
  If you have such a type of relation, then you can apply the equation
  
  x1 * y1 = x2 * y2
  
  where x1 and y1 are the parameters in the first situation, and x2 and y2 are the parameters in the second situation. If x is the number of men working and y represent the number of days, then
  
  x1 = x, original number of men working
  y1 = 10 days
  x2 = x - 10, number of men working on the second situation, which is 10 fewer than the original
  y2 = 10 + 10 = 20 days, number of days on the second situation
  
  Thus, we have
  
  x * 10 = (x - 10) * 20
  10x = 20x - 200
  200 = 10x
  x = 20 men
  
• 11 years agoHelpfull: Yes(2) No(2)
• 20
• 14 years agoHelpfull: Yes(1) No(0)