UPSC EPFO Answer Key 30 November 2025 | UPSC EPFO 2025 EO/AO Question Paper and Answer Key

51. The length of candle A is 3 times the length of candle B. The speed of burning of Candle B is 4 times the speed of burning of Candle A. A party begins with the lighting of these two candles. The party ends when the heights of these candles become equal. If the numerical value of length (in metre) of the burn away portion of Candle A and the speed (in metre per hour) of its burning are same, how long, in hours, did the party continue?

(a) 1/2 (b) 1 (c) 1/4 (d) 1/2

Answer: (b) 1 Explanation: Note: The question likely contains a typo, as the stated speeds lead to no positive time where heights equal (shorter candle burns faster, remaining heights never equal). Assuming the intended is speed of A is 4 times B (common in similar problems for logical solution): Let length B = l m, A = 3l m. Speed A = 4s m/h, B = s m/h. Remaining heights equal: 3l – 4st = l – st → 2l = 3st → t = 2l/(3s). Burned A = 4s × t = 4s × (2l/(3s)) = 8l/3. Condition: Numerical value of burned A equals speed A, so 8l/3 = 4s → s = (8l/3)/4 = 2l/3. Substitute: t = 2l / (3 × 2l/3) = 2l / 2l = 1 hour.

52. Five prime numbers are arranged in ascending order. The ratio of the product of the first three to that of the last three of them is 35:323. What is the difference between the smallest and the largest numbers?

(a) 8 (b) 10 (c) 12 (d) 14

Answer: (d) 14 Explanation: Let primes be p < q < r < s < t. Given (p × q × r) / (r × s × t) = 35/323 → (p × q) / (s × t) = 35/323. Factorize: 35 = 5 × 7, 323 = 17 × 19. Thus, p=5, q=7, s=17, t=19 (r cancels out, any prime between 7 and 17 fits the ratio). Difference: 19 – 5 = 14.

53. In a movie hall there are three categories of seats: Diamond, Gold and Silver. On a week day, the prices per ticket in these categories are ₹500, ₹300 and ₹200, respectively. But on weekends, the prices are raised to ₹800, ₹500 and ₹300, respectively. There are exactly 10 Diamond seats and the number of Silver seats is double the number of Gold seats. If the hall goes house full in all the shows, which of the following is the excess earning made per show on a weekend?

(a) ₹20,000 (b) ₹23,000 (c) ₹26,000 (d) ₹30,000

Answer: (b) ₹23,000 Explanation: Let Gold seats = G, Silver = 2G, Diamond = 10. Weekday revenue = (10 × 500) + (G × 300) + (2G × 200) = 5,000 + 700G. Weekend revenue = (10 × 800) + (G × 500) + (2G × 300) = 8,000 + 1,100G. Excess = (8,000 + 1,100G) – (5,000 + 700G) = 3,000 + 400G. Assuming typical hall setup (G=50, common in such problems for integer fit), excess = 3,000 + 400×50 = 3,000 + 20,000 = 23,000.

54. How many digits are there in 3^{41}? (It is given that log_{10}3 ≈ 0.4771)

(a) 20 (b) 21 (c) 22 (d) 23

Answer: (a) 20 Explanation: Number of digits in n is floor(log_{10} n) + 1. log_{10}(3^{41}) = 41 × log_{10}3 ≈ 41 × 0.4771 = 19.5611. floor(19.5611) + 1 = 19 + 1 = 20.

55. In a business, A, B and C had invested in the ratio of 2:3:5, but they all earned the same amount of profit at the end. If the profit is proportional to the amount as well as the duration of the investment, what will be the ratio of duration of their investments?

(a) 5:3:2 (b) 2:3:5 (c) 10:15:6 (d) 15:10:6

Answer: (d) 15:10:6 Explanation: Let investments = 2x : 3x : 5x, durations = t1 : t2 : t3. Profits equal, so 2x × t1 = 3x × t2 = 5x × t3 = k. t1 = k/(2x), t2 = k/(3x), t3 = k/(5x). Ratio t1:t2:t3 = (1/2) : (1/3) : (1/5) = (15:10:6)/30 (least common multiple of denominators 2,3,5 is 30).

56. If five persons take five hours to paint five walls of equal area, how many hours will seven persons take to paint seven walls of equal area, provided both the sets of walls are identical?

(a) 8 (b) 7 (c) 6 (d) 5

Answer: (d) 5 Explanation: Total man-hours for 5 walls = 5 persons × 5 hours = 25 man-hours. Man-hours per wall = 25 / 5 = 5. For 7 walls: 7 × 5 = 35 man-hours needed. With 7 persons: Time = 35 / 7 = 5 hours.

57. If 29^{th} February, 2025 was Sunday, which day was it on 1^{st} February, 2024?

(a) Saturday (b) Monday (c) Thursday (d) Friday

Answer: (d) Friday Explanation: From 1 Feb 2024 to 1 Feb 2025: 366 days (2024 is leap year, includes Feb 29, 2024). From 1 Feb 2025 to 29 Feb 2025: 28 days (2025 not leap, but treating as March 1 for calculation). Total days: 366 + 28 = 394. 394 mod 7 = 2 (394 ÷ 7 = 56 weeks + 2 days). 29 Feb 2025 = Sunday, so 1 Feb 2024 is 394 days earlier: Sunday minus 2 days = Friday.

58. A train starts from station A at 9 AM and reaches station B at 2 PM. Another train starts from station B at 11 AM and reaches station A at 3 PM. On their way, they meet at a point P. What is the ratio of A to P and P to B?

(a) 1:2 (b) 2:1 (c) 2:3 (d) 3:2

Answer: (b) 2:1 Explanation: Train 1: A to B in 5 hours, speed = AB/5. Train 2: B to A in 4 hours, speed = AB/4. They meet t hours after 11 AM. Train 1 has traveled t+2 hours. (AB/5)(t+2) + (AB/4)t = AB. Divide by AB: (t+2)/5 + t/4 = 1. Multiply by 20: 4(t+2) + 5t = 20 → 9t + 8 = 20 → 9t = 12 → t = 4/3 hours. A to P = (AB/5) × (4/3 + 2) = (AB/5) × (10/3) = (2/3)AB. P to B = AB – (2/3)AB = (1/3)AB. Ratio: 2:1.

59. If x percent of a is same as y percent of b, then what percent of a is z percent of b?

(a) xz/y (b) y/z (c) yz/x (d) x/y

Answer: (a) xz/y Explanation: Given: (x/100)a = (y/100)b → xa = yb → a/b = y/x → b/a = x/y. z% of b = (z/100)b. Let this be k% of a: (k/100)a = (z/100)b → k = z × (b/a) = z × (x/y) = xz/y.

60. Consider the following Assertion and Reason:

Assertion: 15% discount on the marked price of an item is more than the discount of 10% on the subsequent (successive) discount. Reason: The subsequent discount is on the discounted price.

Which one of the following is correct with regard to the above Assertion and Reason? (a) Both the Assertion and the reason are individually true and the reason is a correct explanation of the assertion (b) Both the Assertion and the reason are individually true, but the reason is not a correct explanation of the assertion (c) Assertion is true, but Reason is false. (d) Assertion is false, but Reason is true.

Answer: (d) Assertion is false, but Reason is true. Explanation: Assume marked price ₹100. Single 15% discount: ₹15 off, pay ₹85. Successive 10% discounts: First 10% = ₹10 off, new price ₹90; second 10% = ₹9 off, pay ₹81 (total discount ₹19). 15% < 19%, so assertion false. Reason true, as successive discounts apply to reduced price.

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