Puzzles, arrangements & general mental ability

Answer: (c) 12 जुलाई को रविवार है यदि वर्ष एक अधिवर्ष है।

From 12 January to 12 July is 181 days in an ordinary year and 182 days in a leap year. 182 is exactly 26 weeks, so in a leap year 12 July falls on the same day, Sunday.

1. Days from 12 January to 12 July: January 31, February 28 or 29, March 31, April 30, May 31, June 30.
2. Ordinary year: 181 days = 25 weeks + 6 days, so 12 July is Saturday.
3. Leap year: 182 days = 26 weeks exactly, so 12 July is Sunday.
4. 15 July is then Tuesday (ordinary year) or Wednesday (leap year), never Sunday — (a), (b) and (d) fail.

Remember · Count days between the two dates and divide by 7; the remainder is the number of weekdays to move forward.

Question and answer: UPSC's official GS Paper II (2020, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink · Report an error

Answer: (b) 6

Scan the 26 digits once and mark every place where an odd digit is immediately followed by another odd digit. There are six such places: 5-1, 7-3, 3-9, 5-7, 3-1 and 1-5.

1. Pairs in order: 5-1 ✓, 1-4, 4-7, 7-3 ✓, 3-9 ✓, 9-8, 8-5, 5-7 ✓, 7-2, 2-6, 6-3, 3-1 ✓, 1-5 ✓, 5-8 …
2. After 5-8 the odd digits are 3, 5, 3 and 9, and each is followed by an even digit (8, 2, 4, 6).
3. Total odd-odd pairs = 6.

Remember · For adjacency counts, scan pairs left to right in one pass and tick each hit; do not restart counting.

Question and answer: UPSC's official GS Paper II (2020, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink · Report an error

Answer: (b) 41

G is 11 places to the right of A, so G is 27th from the left. G is also 3 places to the right of V, so V is 24th from the left. V is 18th from the right, so the row has 24 + 18 − 1 = 41 boys.

1. A is 16th from the left; G is 11th to A's right, so G is 16 + 11 = 27th from the left.
2. G is 3rd to V's right, so V is 27 − 3 = 24th from the left.
3. V is 18th from the right, so total = 24 + 18 − 1 = 41.
4. Check: G is then 41 − 27 + 1 = 15th from the right, which is 3 places right of V (18th).

Remember · Convert every position to one end, then total = position from left + position from right − 1.

Question and answer: UPSC's official GS Paper II (2020, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink · Report an error