kanagaraj

• Aug 28th, 2006

 

let x be the distance covered by car. it takes 7 hrs. so the speed of the car is x/7.and while returning back he increases speed by 12km/hrs and he takes 5 hrssox/7=x/5-12km/hrs(speed now equal)by solving this equation we get x=210kms

bhushan_

 Profile Answers by bhushan_ Questions by bhushan_

• Dec 16th, 2008

 

Given, car travel a certain distance in 7 hrs.
 let speed be x.
 so, by formula
    D = ST (D for  distance , S for speed , T for  time)
  D1 = 7x. -----------(statement 1)

now for return journey
Given, In return journey speed increased by12kmph.
means , 12 + x (x is  forward journey speed) 
 time taken by car while returning back 5hrs
so,
D2 = ST
D2 =  (x+12)*5
D2 = 5x+60  -----------(statement 2)

from statement 1 & statement 2
 one thing is clear that in between distance  of forward journey & retuning journey is same.
whatever distance dist. cover by car in forward journey is as same as covered in backward journey.

what we get,
5x+60  =  7x
60 = 2x
x = 30

ANS : 30km.

premkumar.kmar

 Profile Answers by premkumar.kmar 

• Oct 5th, 2009

 

Let x be the distance .

speed = x/7   for onward journey
speed = x/7  + 12 for return journey.

Hence

         7 * x/ 7 = (x/7 +12) * 5
  =>   x       =    (x/7 + 12) * 5
  =>   7x    =      (x + 84) * 5
  =>   7x    =   5x  + 440
  =>   2x =  420
  =>    x = 210

Hence Distance travelled by the car is 210 km.

ganeshbhat

 Profile Answers by ganeshbhat 

• Feb 18th, 2010

 

@Bhushan
You have first said let x be the speed of the car and then finally considered x to be the distance travelled.

ganeshbhat

 Profile Answers by ganeshbhat 

• Feb 18th, 2010

 

Let d be the distance and s be the speed during the forward journey then we have
d=7s

While returning the speed is increased by 12km/hr hence we have
d= 5(s+12)

by the above 2 statements we have
7s=5s+60
s=30;

Hence d=7*30=210

altr

• Feb 6th, 2016

 

30km/hr is the speed. The question is what is the distance traveled.
distance=speed*time
=30*7=210kms

Diwakar Shukla

• May 16th, 2017

 

You have calculated Speed instead of Distance.

Shri

• Jun 11th, 2019

 

x is the speed and not distance i guess