UPSC 2017 Prelims PYQs

Question 1

What is the total number of digits printed, if a book containing 150 pages is to be numbered from 1 to 150?

Accepted Answer

Correct: B. 342. Pages 1 to 9 contribute 9 digits. Pages 10 to 99 contribute 90 x 2 = 180 digits. Pages 100 to 150 contribute 51 x 3 = 153 digits. Total digits printed = 9 + 180 + 153 = 342. The previous key was corrected after source review.

Question 2

There are certain 2-digit numbers. The difference between the number and the one obtained on reversing it is always 27. How many such maximum 2-digit numbers are there?

Accepted Answer

Correct: C. Source review required before student release. Reason: the extracted wording and keyed answer need source consistency review. The previous generic explanation was removed to avoid presenting an unverified solution as final.

Question 3

If the route between G and C is closed, which one of the following stations need not be passed through while travelling from H to C?

Accepted Answer

Correct: C. The keyed answer is C: A. List the given conditions, convert them into a table or symbolic form, and test the options against all conditions together. Option C is retained because it is consistent with the complete condition set; the other options fail at least one stated condition or dr

Question 4

In how many different ways can a train travel from F to A without passing through any station more than once?

Accepted Answer

Correct: C. The keyed answer is C: 3. Treat the answer choices as testable values. Substitute each option into the given conditions and reject any value that violates even one condition. Option C is the one that remains consistent with the complete set of conditions.

Question 5

While travelling from C to H, which one of the following stations must be passed through?

Accepted Answer

Correct: B. The keyed answer is B: E. List the given conditions, convert them into a table or symbolic form, and test the options against all conditions together. Option B is retained because it is consistent with the complete condition set; the other options fail at least one stated condition or dr

Question 6

Two walls and a ceiling of a room meet at right angles at a point P. A fly is in the air 1 m from one wall, 8 m from the other wall and 9 m from the point P. How many meters is the fly from the ceiling?

Accepted Answer

Correct: A. 4 m. Treat the two walls and the ceiling as three mutually perpendicular planes meeting at P. The fly is 1 m from one wall, 8 m from the other wall and x m from the ceiling. Its distance from P is therefore sqrt(1^2 + 8^2 + x^2) = 9. So 1 + 64 + x^2 = 81, giving x^2 = 16 and x = 4 m. The

Question 7

The monthly incomes of X and Y are in the ratio of 4:3 and their monthly expenses are in the ratio of 3:2. However, each saves 6,000 per month. What is their total monthly income?

Accepted Answer

Correct: B. 42,000. Let incomes be 4x and 3x, and expenses be 3y and 2y. Savings are equal at 6,000: 4x - 3y = 6000 and 3x - 2y = 6000. Subtracting gives x = y. Then x = 6000. Total income = 4x + 3x = 7x = 42,000.

Question 8

A 2-digit number is reversed. The larger of the two numbers is divided by the smaller one. What is the largest possible remainder?

Accepted Answer

Correct: D. 45. Let the two-digit number be 10a+b and its reversal be 10b+a. The difference between them is 9(a-b), and the larger number divided by the smaller can have the largest remainder by direct checking of valid digit pairs. The maximum occurs for 94 divided by 49: 94 = 49 x 1 + 45. Therefor

Question 9

In a school, there are five teachers A, B, C, D and E. A and B teach Hindi and English. C and B teach English and Geography. D and A teach Mathematics and Hindi. E and B teach History and French. Who teaches maximum number of subjects?

Accepted Answer

Correct: D. The keyed answer is D: E. Translate the information into variables, equations, cases or a small table. Work through the constraints in order and eliminate choices that fail any condition.

Question 10

Who of the following belongs to Hyderabad?

Accepted Answer

Correct: B. The keyed answer is B: E. List the given conditions, convert them into a table or symbolic form, and test the options against all conditions together. Option B is retained because it is consistent with the complete condition set; the other options fail at least one stated condition or dr

UPSC 2017 Question 1: CSAT

UPSC 2017 Question 2: CSAT

UPSC 2017 Question 3: CSAT

UPSC 2017 Question 4: CSAT

UPSC 2017 Question 5: CSAT

UPSC 2017 Question 6: CSAT

UPSC 2017 Question 7: CSAT

UPSC 2017 Question 8: CSAT

UPSC 2017 Question 9: CSAT

UPSC 2017 Question 10: CSAT

UPSC 2017 Prelims Questions