A certain number 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?

(a) 110 men (b) 130 men (c) 100 men (d) none of these

• 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
  
  Hope this helps!!!!!
• 11 years agoHelpfull: Yes(44) No(20)
• x/10 = x-10/20 20x=10x-100 and x = 100. Therefore x+10 = 110.
• 11 years agoHelpfull: Yes(32) No(68)
• A certain number 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.
  when no of adys are doubled , it means no is men is reduced to half.
  so earlier, there were 10*2= 20 men.
  
• 13 years agoHelpfull: Yes(24) No(38)
• W1*T1= W2*T2
  
  so ;
  x*10 = (x-10)*20
  x=20
  
• 11 years agoHelpfull: Yes(21) No(10)
• ans : none of these
  x-10:x = 10:20
  20x-200 =10x
  10x = 200
  x=20
• 7 years agoHelpfull: Yes(1) No(3)
• x * 10 = (x - 10) * 20
  10x = 20x - 200
  200 = 10x
  x = 20 men
• 7 years agoHelpfull: Yes(1) No(2)
• x * 10 = (x - 10) * 20
  10x = 20x - 200
  200 = 10x
  x = 20 men
• 6 years agoHelpfull: Yes(1) No(1)
• taking options none are satisfying if 10 men less then takes 10 days more means 20 days
  take total men are 20
  20:10=x:10
  x=20
  so original men=20
• 6 years agoHelpfull: Yes(1) No(1)
• X men complete work in 10 days then
  Less than 10 members means x-10, are working 10 more days so 10+10= 20 days
  X---------------10
  X-10------------20
  M1D1=M2D2
  X*10 = (X-10)*20
  10X = 20X-200
  200 =10X
  X=20
• 1 year agoHelpfull: Yes(0) No(0)