In covering a distance of 30 km, Celine takes 2 hours more than Sam. If Celine doubles his speed, then he would take 1 hour less than Sam. Celine's speed is:
5 kmph
6 kmph
6.25 kmph
7.5 kmph

• If C is speed of celine and S is speed of Sam, then
  
  
  30/S = 30/C -2
  30/S = 30/2C+1
  
  hence
  30/C - 2 = 30/2C +1
  30/C - 30/2C = 3
  30/C-15/C =3
  15/C=3
  C= 15/3 = 5 km/hr
• 12 years agoHelpfull: Yes(5) No(0)
• distance always remains constant
  d=(x+2)*v where x is the time taken by sam v is the velocity of celine
  now celine doubles the speed
  d=(x-1)*2*v
  equating these two equations
  (x+2)*v=(x-1)*2*v
  x=4 time taken by sam
  time taken by celine=6
  v=d/t
  v=5kmph
• 12 years agoHelpfull: Yes(2) No(1)
• s=30km
  let time taken by sam=t;
  therefore time taken by celine=t+2;
  now speed of sam=30/t
  speed of celine=30(t+2)
  now when celine doubles it's speed then time=t-1
  so speed=2(intial speed of celine)=2*30/(t+2)
  therefore 2*30/(t+2)=30/(t-1)
  by solving t=4;
  therefor celine speed=30/(t+2)=30/6=5kmph
• 11 years agoHelpfull: Yes(0) No(0)