Correct answer is : a) 3 hours 45 minutes

Explanation

Let, the normal speed be ‘x’
And the time taken in normal speed is ‘t’ minutes.
We know,
Distance = KaTeX parse error: KaTeX doesn't work in quirks mode.
KaTeX parse error: KaTeX doesn't work in quirks mode. In normal speed destination distance is KaTeX parse error: KaTeX doesn't work in quirks mode.

According to the question,
KaTeX parse error: KaTeX doesn't work in quirks mode. of x the train taken time is
KaTeX parse error: KaTeX doesn't work in quirks mode. _{[2 hours 30 minutes = 150 minutes]}
Here, destination distance is
KaTeX parse error: KaTeX doesn't work in quirks mode. _{[destination = speed × time]}

As the destination distance is same, so we can compare both distance.
KaTeX parse error: KaTeX doesn't work in quirks mode.
KaTeX parse error: KaTeX doesn't work in quirks mode.
KaTeX parse error: KaTeX doesn't work in quirks mode.
KaTeX parse error: KaTeX doesn't work in quirks mode. _{[cross multiplication]}
KaTeX parse error: KaTeX doesn't work in quirks mode.
KaTeX parse error: KaTeX doesn't work in quirks mode.
KaTeX parse error: KaTeX doesn't work in quirks mode.
KaTeX parse error: KaTeX doesn't work in quirks mode.
KaTeX parse error: KaTeX doesn't work in quirks mode.The time taken in normal speed is 225 minutes or 3 hours 45 minutes.
Ans: The time taken in normal speed is 225 minutes or 3 hours 45 minutes.