A train runs first $75 \mathrm{~km}$ at a certain uniform speed and next $90 \mathrm{~km}$ at an average speed of $10 \mathrm{~km} / \mathrm{h}$ more than the normal speed. If it takes 3 hours to complete the journey, then how much time will the train take to cover $300 \mathrm{~km}$ with normal speed?
Answer & explanation
Correct answer: option 4
Let train travels 75 km with speed = S km/h
According to question ,
\(\frac{75}{S}\) + \(\frac{90}{S + 10}\) = 3
On solving ,
S = 50 km/h
So Time taken to cover 300 km with normal speed
= \(\frac{Distance}{Speed}\)
= \(\frac{300}{50}\)
= 6 hours