A can do a piece of work in 5 days. B can do it in 8 days. With the assistance of C they completed the work in 3 days. Find in how many days can C alone do it?

• Answer is C alone can do the piece of work in 120 days.
  Let the no.of days that C can finish the work be x
  Then, A+B+C=3 days
  (1/5)+(1/8)+(1/x) = (1/3) => x=120.
• 5 years agoHelpfull: Yes(2) No(0)
• A can do the piece of work in 5 days, so A can complete 1/5 of the work in one day.
  B can do it in 8 days, so in one day B can complete 1/8 of the work.
  If A, B and C together can complete the work in 3 days. So in 1 day they together must do 1/3 rd of the work.
  But in one day A can do only 1/5 of the work and b can do only 1/8 of the work. So the rest must be done by C.
  i.e (1/3) - (1/8) - (1/5) = 1/C (one day's work of C)
  => 1/C = (40 - 15 - 24)/120 = 1/120 of the work.
  Thus in 1 day C can do 1/120 of the work.
  So C alone can complete the work in 120 days.
• 5 years agoHelpfull: Yes(1) No(0)
• LCM of 8,5 is 40
  40 unit of work
  A-8 unit
  B-5 UNIT
  C- 3UNIT
  A+B+C=16
  40-16=24
  24/3 = 8 DAYS
• 5 years agoHelpfull: Yes(0) No(3)