The grass in a school playing field had to be cut.
One man could mow the grass in 4 hours
One man could mow the grass in 5 hours
One man could mow the grass in 6 hours
One man could mow the grass in 8 hours
If they all joined forces to cut the field and they all worked at their individual rates, how long would it take to cut the grass.

• when work together (1/4)+(1/5)+(1/6)+(1/8)=89/120
  total time =120/89=1.348314606 hours
• 10 years agoHelpfull: Yes(38) No(0)
• take lcm of 4,5,6,8=960
  now total time taken=960/(240+192+160+120)=1.34hr
• 10 years agoHelpfull: Yes(11) No(8)
• 1st man efficiency: 100/4=25%
  2nd man efficiency:100/5=20%
  3rd man efficiency:100/6=15.16%
  4th man efficiency: 100/8=12.44%
  so total efficiency=(25+20+15.16+12.44)=82.60%
  total time=100/82.60=1.21hours
• 10 years agoHelpfull: Yes(5) No(5)
• This is a time-work problem.
  Work done by a person in one hour=1/total time to complete
  So, 1hr's work when together is 1/4+1/5+1/6+1/8=89/120
  So, time to complete whole work = 120/89 = 1.34 hrs.
• 10 years agoHelpfull: Yes(5) No(0)
• 1st can do 1/4 work in one day
  2nd can do 1/5 work in one day
  3rd can do 1/6 work in one day
  4th can do 1/8 work in one day
  Hence all together can do (1/4)+(1/5)+(1/6)+(1/8)=89/120
  They can do the work in 1/(120/89)=120/89=1.34hr
  
• 10 years agoHelpfull: Yes(2) No(0)
• when work together (1/4)+(1/5)+(1/6)+(1/8)=89/120
  total time =120/89=1.348314606 hours
• 10 years agoHelpfull: Yes(1) No(0)
• ans=120/89
• 10 years agoHelpfull: Yes(0) No(0)
• work together (1/4)+(1/5)+(1/6)+(1/8)=89/120
  total time =120/89=1.35hrs
• 10 years agoHelpfull: Yes(0) No(0)