20 men can cut 30 trees in 4h. If 4 men leave the job. How many trees will be cut in 12h?

(a)72
(b)80
(c)68
(d)79

• 20 men --> 30 trees --> 4 hrs
  20 men's 1 hr work = 1/4 [ie 1/4 of 30 trees]
  So in 1 hr 20 men can cut 30*1/4 = 15/2 trees
  20 men --> 15/2 trees ---> 1 hr
  1 man --> x
  x = 1/20 * 15/2 => 3/8 tree
  So 1 man can cut 3/8 tree in 1 hr
  
  Now 4 men left the job... Remaining no. of men = (20-4) = 16
  1 man --> 3/8 tree
  16 men --> x trees
  x = 16*3/8 => x=6
  So 16 men can cut 6 trees in 1 hr
  1 hr --> 6 trees
  12 hr --> x trees
  x = 12*6
  x=72 trees
  
  Ans : (a) 72 trees
  
• 10 years agoHelpfull: Yes(14) No(0)
• (a) 72
  
  20M-----------30T------4H
  20*(4/5)=16M----30T----4*(5/4)=5H
  In 5 hours 30 Trees,so in 12 hours, 12*30/5=72 Trees
  
• 10 years agoHelpfull: Yes(0) No(0)
• 30/4=7.5trees in an hr by 20 men
  1 men will cut 7.5 /20 trees pr hr
  so 16 men will cut (7.5/20)*16tree pr hr
  so in 12 hr trees cut = 72 trees
  so the ans is a
• 9 years agoHelpfull: Yes(0) No(0)
• a) 72
  
  20M-----------30T------4H
  20*(4/5)=16M----30T----4*(5/4)=5H
  In 5 hours 30 Trees,so in 12 hours, 12*30/5=72 Trees
• 9 years agoHelpfull: Yes(0) No(0)
• simple...30/20=1.5 for 1 men in 4 hour...so 16men*1.5=24
  for 12 hour....24*3=72
• 9 years agoHelpfull: Yes(0) No(0)