A man reaches his office 30 min late, if he walks from his home at 3 km per hour and reaches 40 min early if he walks 4 km per hour. How far is his office from his house?
Options:
(a) 7km
(b) 14km
(c) 5km
(d) 3km

• b) 14 km.
  
  Let dist.=x
  time taken at 30 kmph : dist/speed = x/3
  time taken at 40 kmph : x/4
  difference between time taken : 40-(-30) = 70mins = 70/60 hours.
  x/3- x/4 = 70/60
  x/12= 7/6
  x=14 km
• 11 years agoHelpfull: Yes(34) No(5)
• Shortcut formulae:
  Distance=time taken*(product of speeds/difference of speeds)
  =(70/60)hrs*(4*3/4-3)
  =14 km
• 11 years agoHelpfull: Yes(15) No(0)
• s1=3km/hr------->30mins late
  s2=4km/hr-------->40mins early,so take
  LCM(3km,4km)=12km(as the distance from home to office is constant)
  so s1 takes 4hrs,s2 takes 3hrs
  siff in times=1hri.e 60mins
  total time is70mins(30 mins late+40 mins early)
  12kms----------->60mins
  x
• 11 years agoHelpfull: Yes(2) No(4)
• nmhkjnk,hhc
• 7 years agoHelpfull: Yes(1) No(2)
• b) 14 km.
  
  Let dist.=x
  time taken 30 kmph : dist/speed = x/3
  time taken at 40 kmph : x/4
  difference between time taken : 40-(-30) = 70mins = 70/60 hours.
  x/3- x/4 = 70/60
  x/12= 7/6
  x=14 kmb) 14 km.
  
  Let dist.=x
  time taken 30 kmph : dist/speed = x/3
  time taken 40 kmph : x/4
  difference b/t time taken : 40-(-30) = 70mins = 70/60 hours.
  x/3- x/4 = 70/60
  x/12= 7/6
  x=14 kmb) 14 km.
  
  Let dist.=x
  time taken at 30 kmph : dist/speed = x/3
  time taken at 40 kmph : x/4
  difference between time taken : 40-(-30) = 70mins = 70/60 hours.
  x/3- x/4 = 70/60
  x/12= 7/6
  x=14 kmb) 14 km.
  
  Let dist.=x
  time taken at 30 kmph : dist/speed = x/3
  time taken at 40 kmph : x/4
  difference between time taken : 40-(-30) = 70mins = 70/60 hours.
  x/3- x/4 = 70/60
  x/12= 7/6
  x=14 kmb) 14 km.
  
  Let dist.=x
  time taken at 30 kmph : dist/speed = x/3
  time taken at 40 kmph : x/4
  difference between time taken : 40-(-30) = 70mins = 70/60 hours.
  x/3- x/4 = 70/60
  x/12= 7/6
  x=14 kmb) 14 km.
  
  Let dist.=x
  time taken at 30 kmph : dist/speed = x/3
  time taken at 40 kmph : x/4
  difference between time taken : 40-(-30) = 70mins = 70/60 hours.
  x/3- x/4 = 70/60
  x/12= 7/6
  x=14 kmb) 14 km.
  
  Let dist.=x
  time taken at 30 kmph : dist/speed = x/3
  time taken at 40 kmph : x/4
  difference between time taken : 40-(-30) = 70mins = 70/60 hours.
  x/3- x/4 = 70/60
  x/12= 7/6
  x=14 km
• 7 years agoHelpfull: Yes(0) No(4)
• Let dist.=x
  time taken at 3 kmph : dist/speed = x/3
  time taken at 4 kmph : x/4
  difference between time taken : 40-(-30) = 70mins = 70/60 hours.
  x/3- x/4 = 70/60
  x/12= 7/6
  x=14 km
• 7 years agoHelpfull: Yes(0) No(0)
• Answer is 5km don't get misleaded
• 6 years agoHelpfull: Yes(0) No(3)
• A speed of 3 km/hr means that you can cover 3km in 1 hour or 60 minutes. That means you can cover 1 km in 60/3 or 20 minutes.
  
  Similarly a speed of 4 km/h means that you can cover a distance of 1 km in 60/4 or 15 minutes.
  
  So you save 5 minutes (20 - 15) to cover 1 km when you increase your speed from 3 kmph to 4 kmph.
  
  Ram is saving 70 minutes in total (30 minutes late vs 40 minutes early).
  
  5 minutes are saved every km.
  
  That means he is travelling 70/5 or 14 km in total.
• 4 years agoHelpfull: Yes(0) No(0)