A man travels a certain distance at 12 km h and returns to the starting point at 9 km h The total ti...........

Quantitative Aptitude (CHSL) Time & distance

A man travels a certain distance at 12 km/h and returns to the starting point at 9 km/h. The total time taken by him for the entire journey is 2 1/3? hours. The total distance (in km) covered by him is:

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Explanation:

Let distance be x
Speed of upward journey = 12 km/hr
Speed for downward (return) journey = 9 km/hr
Total time, t = 2 hr 20 min =
2 + 20/60 hr = 2 + 1/3 = 6+1/3 = 7/3 hr
Let the distance travelled be 'x' km.
Speed = Distance/Time
When speed (upward journey) = 12 km/hr
Time, t = x km/ (12km/hr)
= x/12 hr
(ii) When speed (return journey) = 9 km/hr
Time, t = x km/(9km/hr) = x/9 hr
Therefore, total time taken to complete the journey,
According to question
x/12 + x/9= 7/3
LCM of 12 and 9 is = 36
3x+4x/36 = 7/3
x = 7*36/3*7
x = 12km
So Distance= 12km
He travelled again to starting point hence = 12×2=24km