UPSC Prelims 2002 · General Studies
Question 64: Basic Numeracy
The length of the longest pole that can be placed in a room 12 m long and 9 m wide and 8 m high is
AnswerThe answer is (c).
The longest pole fits along the room's space diagonal, which is the square root of (length squared + width squared + height squared). That is sqrt(144 + 81 + 64) = sqrt(289) = 17 m. Check: 12 squared is 144, 9 squared is 81 and 8 squared is 64, and their sum, 289, is 17 squared. The pole is longer than any single side because it runs corner to opposite corner through the room.
Why each option is right or wrong
- (a) 12 m is just the length of the room.
- (b) 14 m is shorter than the diagonal.
- (c) Right: the space diagonal is 17 m.
- (d) 21 m is length plus width, which is longer than any straight line that fits.
Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2002, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.