1997 General Studies, all questions
UPSC Prelims 1997 · General Studies
Question 141: Basic Numeracy
The length, breadth and height of a room are l, b and h respectively. The perimeter of the ceiling expressed as a percentage of the total area of the four walls is
a100 h
b100/h
ch
dh/100
AnswerThe answer is (b).
The perimeter of the ceiling is 2(l + b). The four walls have a total area of 2(l + b) × h. The ratio of the perimeter to the wall area is 2(l + b) ÷ [2(l + b) × h] = 1/h, and as a percentage it is 100/h. The (l + b) cancels, so the answer depends only on the height.
Why each option is right or wrong
- (a) 100h inverts the ratio.
- (b) Right: 100/h.
- (c) h is not the percentage; the ratio is 1/h.
- (d) h/100 inverts the ratio and also mis-scales it.
Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 1997, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.