Robert is travelling on his cycle and has calculated to reach point A at 2 P.M. if he travels at 10 kmph, he will reach there at 12 noon if he travels at 15 kmph. At what speed must he travel to reach A at 1 P.M.?

A. 8 kmph
B. 11 kmph
C. 12 kmph
D. 14 kmph

• Average speed= 2xy/x+y
  where x=10, y=15
  Required speed=(2*10*15)/(10+15)=300/25=12kmph
• 12 years agoHelpfull: Yes(26) No(4)
• 
  Let the distance travelled by x km.
  x/10 - x/15 =2
  x=60
  Time taken to travel 60 km at 10 km/hr = 60/10 =6hrs.
  
  So, Robert started 6 hours before 2 P.M. i.e., at 8 A.M.
  Required speed = 60/5 =12kmph
• 11 years agoHelpfull: Yes(26) No(1)
• distance that has to be travelled by Robert is 'x' (let).
  
  now,
  
  (x/10) - (x/15) = 2
  x =60kms, so he starts at 8am. now to reach at 1 pm, time =5hrs, distance = 60kms, find speed. 12kmph
• 8 years agoHelpfull: Yes(1) No(0)