Lakshmi and Divya can complete a data entry jobin X days. Lakshmi alone takes 9 days more to finish the work while Divya take 4 days more. Find the value of X.

(a) 5 days
(b) 13 days
(c) 6 days
(d) 9 days

• (c) 6 days
  
  Working alone Lakshmi takes X+9 days and Divya takes X+4 days.
  So working together their 1 day work= 1/(X+9) + 1/(X+4) = 1/X
  => (X+4+X+9)/[(X+9)(X+4)] = 1/X
  => 2X^2+13X = X^2 +4X+9X+36
  => X^2= 36
  => X=6
• 7 years agoHelpfull: Yes(0) No(1)
• Working alone Lakshmi takes X+9 days and Divya takes X+4 days.
  So working together their 1 day work= 1/(X+9) + 1/(X+4) = 1/X
  => (X+4+X+9)/[(X+9)(X+4)] = 1/X
  => 2X^2+13X = X^2 +4X+9X+36
  => X^2= 36
  => X=+/-6
  but time can't be negative
  hence 6 is corret
• 7 years agoHelpfull: Yes(0) No(0)