UPSC CDS I 2025 Mathematics Paper

A man is traveling at 3∕5 th of his usual speed and is late by 20 minutes.
Formula used:
Time = Distance ÷ Speed
Let the usual time taken by the man be T minutes.
When traveling at 3/5th of the usual speed, time taken =T×(5∕3).
Difference in time: T×(5∕3)−T=20 minutes.
Calculation:
‌⇒T×(5∕3)−T=20
‌⇒(5T∕3)−T=20
‌⇒(5T−3T)∕3=20
‌⇒2T∕3=20
‌⇒T=20×(3∕2)
‌⇒T=30‌ minutes ‌