.the tcs office at siruseri is at a distance of 21km from baburaj’s home.when he leaves home 10 minutes late his travel time increases by 40% if leaving late decreases his average speed by 12kmph how long does his commute take when he leaves on time a)1 hour b)21minutes c)30 minutes d)40 minutes

• Let his travel time be 'x' when he leaves for his office on time.
  When he leaves home 10 minutes late his travel time becomes (x+(40/100)*x) which is equal to (7x/5).
  Therefore,His speed when he leaves home 10 minutes late=(21)divided by(7x/5)=15/x.
  His average speed when he leaves on time=21/x.
  According to the question,
  (15/x)=(21/x)-12
  Solving the above equation, we get x=(1/2) hour=30 minutes.
• 9 years agoHelpfull: Yes(12) No(2)
• When he starts at right time travel time=t
  When he starts at 10 min late travel time=1.4t
  21/t - 21/1.4t =12
  Solving we get t=1/2=30 min
• 9 years agoHelpfull: Yes(11) No(0)
• S*t=21;
  S-12*(1.4t+10/60)=21;...try solving this using options convert mins to hrs ...ie if 20 mins then 20/60..try to solve u ll find ans as 40/60 ie 40mins
  
• 9 years agoHelpfull: Yes(4) No(5)
• Let time taken by him when he leaves on right time = t
  and average speed will be 21/t
  
  then time taken by him when he leaves 10 min late = 1.4t
  and average speed = 21/t-12
  
  distance is constant so , 21/t*t = 1.4t/10(21/t-12)
  
  solving the above eq.we get t= 0.5 hr or 30 minutes
  
  
• 9 years agoHelpfull: Yes(3) No(1)
• time=30mins
• 9 years agoHelpfull: Yes(0) No(0)
• @prajukta can u plz explain....
  Regards
  
• 9 years agoHelpfull: Yes(0) No(0)
• S=d/t;S= 21*3/2=31.5-->1
  31.5-12*(1.4*40/60+10/60)..solving this you ll get approx 21.45 which is more or less equal to 21..
  
• 9 years agoHelpfull: Yes(0) No(0)
• (C) - 30 is the answer.
  
• 9 years agoHelpfull: Yes(0) No(0)
• In d same case you are telln 30 mins where that 10 mins in the que went away??
• 9 years agoHelpfull: Yes(0) No(0)