A train takes $2\frac{1}{2}$ hours less for a journey of 300 km, if its speed is increased by 20 km/h from its usual speed. How much time will it take to cover a distance of 192 km at its usual speed ?
Answer & explanation
Correct answer: option 3
Let Speed of train = S km/h
Time = 2\(\frac{1}{2}\) = \(\frac{5}{2}\) hours
According to question ,
\(\frac{300}{S}\) - \(\frac{300}{S+20}\) = \(\frac{5}{2}\)
\(\frac{300(S+20) - 300S}{S(S+20)}\) = \(\frac{5}{2}\)
On solving ,
S = 40 km/h
So , Time required to cover 192km is = \(\frac{192}{40}\) = 4.8 hours