Two people enter a race in whick you run to a point and back. Person A runs 20 mph to and from the point. Person B runs to the point going 10 mph and 30 mph going back. Who came in first?

• Person A will reach first.
  
  Let the distance be x
  Person A :
  Total time = x/20 + x/20
  = x/10
  = .1x
  Person B :
  Total time = x/10 + x/30
  = x/30
  = .133x
  
  Since Time taken by person B is more than person A
  So Person A will reach earlier.
• 12 years agoHelpfull: Yes(6) No(1)
• Obviously, First person will come first.
  By the time, second person covered one way distance , First person has reached back to starting point as speed of First person is exactly double as compared to second person.
  No need to calculate any time.
• 12 years agoHelpfull: Yes(5) No(0)
• First person will come first.
  
  If one side distance is 60 miles,
  
  time taken by first person = 2*60/20 = 6 hrs
  time taken by second person = 60/10 + 60/30 = 8 hrs
• 12 years agoHelpfull: Yes(1) No(1)
• first person average speed = 20 mph
  n second person average speed= 2*10*30/(10+30)==>600/40=15
  so first person comes first.
• 12 years agoHelpfull: Yes(0) No(0)
• ans : A
  avg speed s = 2*20*20/(20+20) = 20 m /hr
  b = 2*10*30/(10+30) = 15 m /hr
  so A comes first
• 11 years agoHelpfull: Yes(0) No(0)
• Let's assume that the distance between start and the point
  is D miles.
  
  Total time taken by Person A to finish
  
  = (D/20) + (D/20)
  
  = D/10
  
  = 0.1D
  
  Total time taken by Person B to finish
  
  = (D/10) + (D/30)
  
  = 2D/15
  
  = 0.1333D
  
  Thus, Person A is the Winner.
  
  Alternatively (if you don't like mathematics ;)), analyse
  the situation as follow:
  
  Note that initially speed of Person A (20 mph) was twice the
  speed of Person B (10 mph). Hence, when Person A (20 mph
  forward) reached the point, Person B (10 mph forward) was
  halfway. When Person A (20 mph back) finished, Person B
  (still 10 mph forward) reached the point.
  
  Thus, Person A wins the race and by that time Person B
  covers only half the distance, no matter how far the point is!!!
  
• 11 years agoHelpfull: Yes(0) No(1)