If a train runs at 40 km/hour, it reaches its destination late by 11 minutes. But if it runs at 50 km/hour, it is late by 5 minutes only. The correct time (in minutes) for the train to complete the journey is

If the distance be $x mathrm{~km}$, then $frac{x}{40}-frac{x}{50}=frac{6}{60}$

$Rightarrow frac{x}{4}-frac{x}{5}=1$

$Rightarrow x=20 mathrm{~km}$

$herefore$ Required time $=left(frac{20}{40} ight)$ hour $-11$ minutes

$herefore$ Required time $=left(frac{20}{40} ight)$ hour $-11$ minutes

$=left(frac{1}{2} imes 60-11 ight)$ minutes $=19$ minutes