2010 General Studies, all questions

UPSC Prelims 2010 · General Studies

Question 33: Basic Numeracy

Running at a speed of 60 km per hour, a train passed through a 1·5 km long tunnel in two minutes. What is the length of the train ?

a250 m
b500 m
c1000 m
d1500 m

AnswerThe answer is (b).

At 60 km per hour the train covers 1 km a minute, so in 2 minutes it travels 2 km, or 2000 m. To pass completely through the tunnel it must cover the tunnel's length plus its own length: 2000 m = 1500 m + train length, so the train is 500 m long. Remember: to cross a tunnel or bridge, distance = length of tunnel + length of train.

Why each option is right or wrong
  • (a) 250 m would make the distance only 1750 m.
  • (b) Right: 2000 - 1500 = 500 m.
  • (c) 1000 m would make the distance 2500 m.
  • (d) 1500 m would make the distance 3000 m.

Explanation: written by UPSC Grade, not by UPSC.

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Source: UPSC, Civil Services (Preliminary) Examination 2010, General Studies, Series A. The paper on upsc.gov.in.