2002 General Studies, all questions
UPSC Prelims 2002 · General Studies
Question 128: Basic Numeracy
Assume that the moon takes exactly 30 days to complete the cycle and also assume that it rises in the East exactly at 6.48 p.m. on the first day. On the fourth day, at what time will it rise?
a8.24 p.m.
b9.12 p.m.
c10.00 p.m.
d11.48 p.m.
AnswerThe answer is (b).
If the moon takes 30 days to complete its cycle, moonrise comes 24 h x 60 / 30 = 48 minutes later each day. From the first day (6:48 p.m.) to the fourth day is three steps: 3 x 48 = 144 minutes = 2 h 24 min. So moonrise on the fourth day is 6:48 p.m. + 2:24 = 9:12 p.m.
Why each option is right or wrong
- (a) 8:24 p.m. adds only 1 h 36 min, which is two steps of 48 minutes.
- (b) Right: three steps of 48 minutes give 9:12 p.m.
- (c) 10:00 p.m. adds 3 h 12 min, which is four steps.
- (d) 11:48 p.m. adds 5 hours, far more than three steps.
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.