A car is travelling at a uniform speed.
The driver sees a milestone showing a 2-digit number.
After travelling for an hour the driver sees another milestone with the same digits in reverse order.
After another hour the driver sees another milestone containing the same two digits.
What is the average speed of the driver.

• FIRSTLY, the Question is not complete.
  SOLUTION
  the first milestone seen by the driver is 2 digited. let it be ... 10x + y ..(1)
  After 1 hr
  the second milestone is in reversed order. it must be ... 10y + x ....(2)
  again after 1 Hr
  the third milestone having same digit bt their is zero btween the to digitsit is given as ... 100x + 0*10 + y = 100x + y ....(3)
  from eqn 2 and 3, we get
  {(100x + y) - (10y + x)}/1 = speed of the car .... {Distance = speed * time}
  therefore speed of the car = 99x - 9y .. (4)
  from 1 1nd 2 ,we get
  9y - 9x = speed of the car ....(5)
  from eqn 4 and 5,we get
  9y - 9x = 99x - 9y
  or y - x = 11x - y
  or y = 6x ... (6)
  substituting this value in the eqns 1 and 2, we get
  10x + 6x = 16x (the first milesztone)
  10*6x + x = 61x (the second milestone)
  Speed of the car = (distance between two milestone)/time
  = (61x - 16x)/1
  = 45x km/hr
  On seeing the option we can select our answer.
  by just putting x = 1,2,3,4,....................
  
  
• 12 years agoHelpfull: Yes(20) No(2)
• Here uniform speed is given so
  Let assume first milestone will contain =xy
  second=yx
  third would be the combination of these two so x0y or y0x
  Driver travels yx-xy in a hour and x0y-yx or y0x-yx in another one hour
  Speed=Distance/Time
  (yx-xy)/1=(x0y-yx)/1
  {Due to uniform speed}
  (10*y+x)-(10*x+y)=(100*x+0*10+y)-(y*10+x)
  after solving we'll have x/y=1/6 or y=6x
  put the value x=1,2,3.....
  for x=1
  Speed=61-16=45 Km/Hr
• 12 years agoHelpfull: Yes(7) No(0)
• milestones are 16,61 and 106
  so speed is 45 mph if milestone is giving distance in miles.
• 12 years agoHelpfull: Yes(5) No(5)
• average speed is 25.66km/hr
  first he sees 25km milostone
  then he sees 52km milestone
  and at last he sees 77km milestone.....
  25 reverse digit 52 and then same two digit contg. no.
• 12 years agoHelpfull: Yes(2) No(7)
• @ashutosh sing
  if we put x=1 then y=6, so that first mile stone is 16 km, car speed is 16kmph
  given car travelling uniform speed then 2nd milestone at 61 and 3rd 601 impossible (according to question)
  
• 9 years agoHelpfull: Yes(0) No(3)