An express train makes a run of 240 km at a certain speed. Another train whose speed is 12 km/hr less takes an hour longer to cover the same distance. Find the speed of the express train in km/hr.
Share
An express train makes a run of 240 km at a certain speed. Another train whose speed is 12 km/hr less takes an hour longer to cover the same distance. Find the speed of the express train in km/hr.
Sign Up to our social questions and Answers Engine to ask questions, answer people’s questions, and connect with other people.
Login to our social questions & Answers Engine to ask questions answer people’s questions & connect with other people.
Step-by-step explanation:
Given : Total Distance = 240 km
Difference 1 hrs
Find : The Speed Of The Express Train in km / hr
Solutions : Let Speed be x km / hr
Therefore time 240/x hrs
New Speed = x - 12 km / hr
Therefore time = 240/ x - 12 hrs
Now Applying Cross Multiplication Method
Therefore 240 / x - 12 - ( 240 / x ) = 1
240 x - 240 x + 2880 / x ^ 2 - 12 x = 1
2880 = x ^2 - 12 x ( Now Transpoising R H S To L H S )
x ^2 - 12 x - 2880 = 0
By Completing The Square
x = 60
x = 48
The Speed Is Always Positive Not Negative
So The Original Speed Of Train is 60 km / hr