Minimalist IAS
CSAT 2023 paper

UPSC CSE CSAT 2023 · Paper II (CSAT) · Question 65 · Counting, permutations & probability

किसी परीक्षा में, चार प्रश्न-पत्रों, नामतः P, Q, R और S में से प्रत्येक प्रश्न-पत्र के लिए अधिकतम…

UPSC Civil Services (Preliminary) Examination 2023, General Studies Paper II (CSAT), Question 65 — Counting, permutations & probability.

CSAT 2023 · Q65

Counting, permutations & probability Medium

किसी परीक्षा में, चार प्रश्न-पत्रों, नामतः P, Q, R और S में से प्रत्येक प्रश्न-पत्र के लिए अधिकतम अंक 100 हैं । विद्यार्थियों द्वारा प्राप्त किए गए अंक पूर्णांकों में हैं । कोई भी विद्यार्थी n विभिन्न तरीकों से 99% प्राप्तांक ला सकता है । n का मान क्या है ?

Read this question in English

In an examination, the maximum marks for each of the four papers namely P, Q, R and S are 100. Marks scored by the students are in integers. A student can score 99% in n different ways. What is the value of n?

(a) 16 · (b) 17 · (c) 23 · (d) 35

उत्तर और व्याख्या · explanation in English

Answer: (d) 35

99% of 400 is 396, so the student loses exactly 4 marks in all across the four papers. Sharing 4 lost marks among 4 papers (0 or more each) can be done in C(7, 3) = 35 ways.

  1. Total maximum = 4 × 100 = 400; 99% of 400 = 396.
  2. Let the marks lost in P, Q, R, S be w, x, y, z (each 0 or more) with w + x + y + z = 4; no paper can exceed 100.
  3. Number of solutions = C(4 + 3, 3) = C(7, 3) = 35.
  4. Check by cases: (4,0,0,0) type 4 ways, (3,1,0,0) 12, (2,2,0,0) 6, (2,1,1,0) 12, (1,1,1,1) 1 → 35.

Remember · Count marks lost instead of marks scored; n identical units in r boxes can be shared in C(n + r − 1, r − 1) ways.

Question and answer: UPSC's official GS Paper II (2023, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). ·

Cite this question: UPSC CSE CSAT 2023, Q65 — minimalistias.com/pyqs/csat/2023/q65

In the UPSC syllabus: Counting, permutations & probability › Permutations & combinations See it and tick it covered →

Timed · 35 minutes Take CSAT Counting, permutations & probability · Set 1 as a test This question is in it — with UPSC's marking and an instant score. Start the set

More on Counting, permutations & probability

All Counting, permutations & probability questions →