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Question:  A car is traveling at a uniform speed. The driver sees a milestone showing a 2-digit number. After traveling 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 with a zero in between(0). What is the average speed of the driver.

PLEASE EXPLAIN STEP WISE



September 09, 2007 04:59:48 #1
 swamidayalsrivastava   Member Since: Visitor    Total Comments: N/A 
RE: A car is traveling at a uniform speed. The driver ...
 

Let 10'splace digit is x and unit's place digit y

First milestone :      10x+y
Second milestone : 10y+x
Third milestone:      100x+y

Since the speed is uniform so
  Distance covered in first Hr = Distance covered in Second Hr
  (10y+x)-(10x+y) = (100x+y)-(10y+x)
After solving, we get  ---->   y=6x  but since x and y are digits so only possible combination is x=1 and y=6,
  So average speed = 45 KM/HR

     

 

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