Question
Wed March 04, 2015 By: Sriradha Gupta

 
A train covers a certain distance at uniform speed. if the speed is increased by 20 km/hr, it would take 5 hours less for the journey. if the speed is reduced by 12 km/hr, it would take 5 hrs more. find the uniform speed of the train and the distance covered.
 

Expert Reply
Rohit Ranawat
Thu March 05, 2015
l e t space s p e e d o f space t h e space b u s space b e space a space k m divided by h r space a n d space t i m e space t a k e n space b e space b space h r s d i s tan c e space equals space a b space k m  left parenthesis a plus 15 right parenthesis left parenthesis b minus 2 right parenthesis space equals space a b minus 2 a space plus space 15 b space equals space 30.... left parenthesis 1 right parenthesis  left parenthesis a minus 5 right parenthesis left parenthesis b plus 1 right parenthesis space equals space a b a minus 5 b space equals space 5.... left parenthesis 2 right parenthesis  m u l t i p l y space e q u a t i o n space left parenthesis 2 right parenthesis space b y space 2 comma space t h e n space a d d space left parenthesis 1 right parenthesis space a n d space left parenthesis 2 right parenthesis comma space w e space g e t 5 b space equals space 40 b space equals space 8  p u t space b space equals space 8 space i n space e u a t i o n space left parenthesis 2 right parenthesis comma space w e space g e t a space equals space 45  u n i f o r m space s p e e d space equals space 45 space k m divided by h r d i s tan c e space c o v e r e d space equals space a space asterisk times b equals space 45 space asterisk times space 8 equals 360 space k m space space
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