Q. If P means ‘greater than (>)’; Q means less than (<)’; R means ‘not greater than (>)’; S means ‘not less than (<)’ and T means ‘equal to (=)’, then consider the following statements:
1. If 2x(S)3y and 3x(T)4z, then 9y(P)8z. 2. If x(Q)2y and y(R)z, then x(R)z. Which of the statements given above is/are correct? a) 1 only b) 2 only c) Both 1 and 2 d) Neither 1 nor 2 Correct answer: d) Neither 1 nor 2
Question from UPSC Prelims 2024 CSAT
Explanation :
Statement 1: “If 2x is not less than 3y AND 3x equals 4z, then 9y is greater than 8z”
Analysis: 1. From 3x equals 4z, we can say x equals 4z/3 2. Putting this in first condition: 2(4z/3) is not less than 3y 3. Simplifying: 8z/3 is not less than 3y 4. Multiplying both sides by 3: 8z is not less than 9y 5. Therefore: 9y is less than or equal to 8z 6. But statement claims 9y is greater than 8z 7. This is a contradiction
Statement 2: “If x is less than 2y AND y is not greater than z, then x is not greater than z”
Analysis: 1. From first condition: x < 2y 2. From second condition: y ≤ z 3. Putting these together: x < 2z 4. However, x < 2z does not guarantee that x ≤ z 5. Counter example: Let z = 1, y = 1, x = 1.9 – Here x < 2y is true (1.9 < 2) – y ≤ z is true (1 ≤ 1) – But x ≤ z is false (1.9 is not ≤ 1)
Q. If a+b means a-b; a-b means axb; axb means a÷b; a÷b means a+b, then what is the value of 10+30-100 x 50÷25? (Operations are to be replaced simultaneously)
a) 15 b) 0 c) -15 d) -25 Correct answer: d) -25
Question from UPSC Prelims 2024 CSAT
Explanation :
Original Expression: 10 + 30 – 100 x 50 / 25
Replacing each operator simultaneously: The plus sign (+) becomes minus (-) The minus sign (-) becomes multiply (x) The multiply sign (x) becomes divide (/) The divide sign (/) becomes plus (+)
After replacing all operators at once, the expression becomes: 10 – 30 x 100 / 50 + 25
Now let’s solve this expression following standard order of operations:
First step: Work out multiplication 30 x 100 equals 3000
Second step: Work out division 3000 / 50 equals 60
Third step: The expression is now 10 – 60 + 25
Fourth step: Work from left to right with subtraction and addition 10 minus 60 equals -50 -50 plus 25 equals -25
Q. A Main Statement is followed by four Statements labelled P, Q, R and S. Choose the ordered pair of the Statements where the first Statement implies the second, and the two Statements are logically consistent with the Main Statement.
Main Statement: Pradeep becomes either a Director or a Producer.
Statement P: Pradeep is a Director
Statement Q: Pradeep is a Producer.
Statement R: Pradeep is not a Director.
Statement S: Pradeep is not a Producer.
Select the correct answer. a) SP only b) RQ only c) Both SP and RQ d) Neither SP nor RQ Correct answer: c) Both SP and RQ
Question from UPSC Prelims 2024 CSAT
Explanation :
Given main statement: Pradeep becomes either a Director or a Producer
Let’s define: D = Pradeep is a Director P = Pradeep is a Producer R = Not Director S = Not Producer
Analyzing statement pairs:
1. S implies P: – If S is true (Not Producer) – From main statement (must be Director or Producer) – Then D must be true (Director) This is valid
2. R implies Q: – If R is true (Not Director) – From main statement (must be Director or Producer) – Then P must be true (Producer) This is valid
Both pairs are logically valid based on the main statement that Pradeep must be either Director or Producer.
Q. Age of each of P and Q is less than 100 years but more than 10 years. If you interchange the digits of the age of P, the number represents the age of Q.
Question: What is the difference of their ages?
Statement-I: The age of P is greater than the age of Q.
Statement-II: The sum of their ages is 11/6 times their difference.
Which one of the following is correct in respect of the above Question and the Statements? a) The Question can be answered by using one of the Statements alone, but cannot be answered using the other Statement alone b) The Question can be answered by using either Statement alone c) The Question can be answered by both the Statements using together, but cannot be answered using either Statement alone d) The Question cannot be answered even by using both the Statements together Correct answer: a) The Question can be answered by using one of the Statements alone, but cannot be answered using the other Statement alone
Question from UPSC Prelims 2024 CSAT
Explanation :
Given: – P and Q are two-digit ages – P = 10a + b – Q = 10b + a where a and b are digits (1-9)
Statement I: P is greater than Q
– This means 10a + b > 10b + a – Simplifies to a > b – Multiple values possible – Not sufficient alone
Statement II: Sum of ages is 11/6 times their difference
– (P + Q) = 11/6 × (P – Q) – (10a + b) + (10b + a) = 11/6 × [(10a + b) – (10b + a)] – 11a + 11b = 11/6 × (9a – 9b) – 66(a + b) = 99(a – b) – 5b = a
Since a and b must be single digits: – Only possible solution is a = 5, b = 1 – Therefore P = 51 and Q = 15 Statement II alone is sufficient.
Answer: a) The question can be answered using Statement II alone, but cannot be answered using Statement I alone.
Q: What is the time required to download the software?
Statement-I: The size of the software is 12 megabytes.
Statement-II: The transfer rate is 2.4 kilobytes per second.
Which one of the following is correct in respect of the above Question and the Statements? a) The Question can be answered by using one of the Statements alone, but cannot be answered using the other Statement alone b) The Question can be answered by using either Statement alone c) The Question can be answered by using both the Statements together, but cannot be answered using either Statement alone d) The Question cannot be answered even by using both the Statements together. Correct answer: c) The Question can be answered by using both the Statements together, but cannot be answered using either Statement alone
Question from UPSC Prelims 2024 CSAT
Explanation :
Statement I Alone:
– Knowing only the size (12 MB) isn’t enough to find download time – Need transfer rate to calculate time
Statement II Alone:
– Knowing only transfer rate (2.4 KB/s) isn’t enough – Need file size to calculate time
Both Statements Together: 1. Convert 12 megabytes to kilobytes: 12 MB = 12 × 1024 = 12,288 KB
Q: What are the values of m and n where m and n are natural numbers?
Statement-I: m+n > mn and m > n.
Statement-II: The product of m and n is 24.
Which one of the following is correct in respect of the above Question and the Statements? a) The Question can be answered by using one of the Statements alone, but cannot be answered using the other Statement alone b) The Question can be answered by using either Statement alone c) The Question can be answered by using both the Statements together, but cannot be answered using either Statement alone d) The Question cannot be answered even by using both the Statements together Correct answer: c) The Question can be answered by using both the Statements together, but cannot be answered using either Statement alone
Question from UPSC Prelims 2024 CSAT
Explanation :
Statement I Alone:
1. Rearranging m + n > mn gives (m-1)(n-1) < 1 2. Since m and n are natural numbers, and m > n: – n must equal 1 – m can be any natural number > 1 This alone doesn’t give unique values.
Statement II Alone:
1. Factors of 24 give these pairs: (1,24), (2,12), (3,8), (4,6), (6,4), (8,3), (12,2), (24,1) This alone doesn’t give unique values.
Both Statements Together: 1. From Statement I, n must be 1 2. From Statement II, mn = 24 3. Substituting n = 1: m × 1 = 24 Therefore m = 24
The unique solution is m = 24 and n = 1.
Answer: c) The question can be answered using both statements together, but cannot be answered using either statement alone.
Statement: India is the world’s largest producer of milk.
Conclusion-I: India is the world’s largest exporter of milk.
Conclusion-II: India does not import milk.
Which one of the following is correct? a) Only Conclusion-I follows b) Only Conclusion-II follows c) Both Conclusion-I and Conclusion-II follow d) Neither Conclusion-I nor Conclusion-II follows Correct answer: d) Neither Conclusion-I nor Conclusion-II follows
Question from UPSC Prelims 2024 CSAT
Explanation :
Conclusion-I: India is the world’s largest exporter of milk. Analysis: Being largest producer doesn’t mean largest exporter. Production and export are different metrics. India might consume most milk domestically rather than export.
Conclusion-II: India does not import milk. Analysis: Being largest producer doesn’t mean no imports. A country can both produce and import based on various factors like regional demand and quality requirements.
Answer: d) Neither Conclusion-I nor Conclusion-II follows
Question: Has P scored more marks than Q? Statement-I: The sum of the marks scored by P and Q is equal to the sum of the marks scored by R and S.
Statement-II: The sum of the marks scored by P and S is more than the sum of the marks scored by Q and R.
Which one of the following is correct in respect of the above Question and the Statements? a) The Question can be answered by using one of the Statements alone, but cannot be answered using the other Statement alone b) The Question can be answered by using either Statement alone c) The Question can be answered by using both the Statements together, but cannot be answered using either Statement alone d) The Question cannot be answered even by using both the Statements together. Correct answer: d) The Question cannot be answered even by using both the Statements together.
Question from UPSC Prelims 2024 CSAT
Explanation :
Analyzing Statement I Alone:
P + Q = R + S This only shows sum of P and Q equals sum of R and S. Examples: P = 7, Q = 5, R = 4, S = 8 → P > Q P = 6, Q = 6, R = 5, S = 7 → P = Q P = 5, Q = 7, R = 4, S = 8 → P < Q Statement I alone insufficient.
Analyzing Statement II Alone:
P + S > Q + R Shows P and S together score more than Q and R. Examples: P = 7, S = 5, Q = 5, R = 4 → P > Q P = 3, S = 6, Q = 4, R = 3 → P < Q Statement II alone insufficient.
Combining Statements:
From I: P + Q = R + S → P = R + S – Q From II: P + S > Q + R → S > Q Substituting: P = R + (S – Q) Examples: If R = 35, S = 60, Q = 50 → P = 45 → P < Q If R = 41, S = 60, Q = 50 → P = 51 → P > Q Combined statements still insufficient.
Answer: d) The Question cannot be answered even by using both the Statements together.