CSAT 2020

Q. A is 16th from the left end in a row or boys and V is 18th from the right end. Q is 11th from A towards the right and 3rd from V towards the right end. How many boys are there in the row? 

Q. A is 16th from the left end in a row or boys and V is 18th from the right end. Q is 11th from A towards the right and 3rd from V towards the right end. How many boys are there in the row?

(a) 40
(b) 41
(c) 42
(d) Cannot be determined due to insufficient data
Correct Answer: (b) 41

Question from UPSC Prelims 2020 CSAT Paper

Explanation : 

A is 16th from the left end in a row

Q is 3rd from V towards the right, so position of Q = 18 – 3 = 15th from right end.
Q is 11th from A towards the right, so position of Q = 16 + 11 = 27th from left end.
Hence, total number of boys in the row = 27 + 15 – 1 = 41 (we subtract one because Q has been counted twice)

Q. A is 16th from the left end in a row or boys and V is 18th from the right end. Q is 11th from A towards the right and 3rd from V towards the right end. How many boys are there in the row?  Read More »

Q. Two Statements are given followed by two Conclusions:  Statements:  All cats are dogs. All cats are black. 

Q. Two Statements are given followed by two Conclusions:
Statements:
All cats are dogs. All cats are black.

Conclusion-l:
All dogs are black.
Conclusion-ll:
Some dogs are not black.
Which of the above Conclusions logically follows/follow from the two given Statements disregarding commonly known facts?
(a) Only Conclusion-l
(b) Only Conclusion-II
(c) Neither Conclusion-I nor Conclusion-II
(d) Both Conclusions-I and Conclusion-Il
Correct Answer: (c) Neither Conclusion-I nor Conclusion-II

Question from UPSC Prelims 2020 CSAT Paper

Explanation : 

All cats are dogs. All cats are black.

The two given statements are “All cats are dogs” and “All cats are black.” From these statements, we can’t conclude anything about the color of dogs. The first conclusion “All dogs are black” assumes that all dogs are cats, which is not stated in the given statements.

The second conclusion “Some dogs are not black” also assumes something about the color of dogs that is not stated in the given statements. Therefore, neither conclusion logically follows from the two given statements disregarding commonly known facts.

So the correct answer is © Neither Conclusion-I nor Conclusion-II.

Q. Two Statements are given followed by two Conclusions:  Statements:  All cats are dogs. All cats are black.  Read More »

Q. Two Statements are given followed by two Conclusions:  Statements:  All numbers are divisible by 2. All numbers are divisible by 3. 

Q. Two Statements are given followed by two Conclusions:
Statements:
All numbers are divisible by 2.
All numbers are divisible by 3.

Conclusion-l
All numbers are divisible by 6.
Conclusion-II
All numbers are divisible by 4.
Which of the above Conclusions logically follows/follow from the two given Statements?
(a) Only Conclusion-l
(b) Only Conclusion-II
(c) Neither Conclusion-I nor conclusion-Il
(d) Both Conclusions-I and Conclusion-II
Correct Answer: (a) Only Conclusion-l

Question from UPSC Prelims 2020 CSAT Paper

Explanation : 

Conclusion-I states that all numbers are divisible by 6. This conclusion is true because 6 is the least common multiple of 2 and 3. Therefore, any number that is divisible by both 2 and 3 must also be divisible by 6.

Conclusion-II All numbers are divisible by 4.

All numbers that are divisible by 2 and 3 may not be divisible by 4. For example, 6 is divisible by 2 and 3 but not divisible by 4.

Q. Two Statements are given followed by two Conclusions:  Statements:  All numbers are divisible by 2. All numbers are divisible by 3.  Read More »

Q. A man walks down the backside of his house straight 25 meters, then turns to the right and walks 50 meters again; then he turns towards left and again walks 25 meters. If his house faces to the East, what is his direction from the starting point? 

Q. A man walks down the backside of his house straight 25 meters, then turns to the right and walks 50 meters again; then he turns towards left and again walks 25 meters. If his house faces to the East, what is his direction from the starting point?

(a) South-East
(b) South-west
(c) North-East
(d) North-west
Correct Answer: (d) North-west

Question from UPSC Prelims 2020 CSAT Paper

Explanation : 

A man walks down

The man starts at the back of his house facing East. He then walks 25 meters straight down the backside of his house. Since he is walking away from the house and the house faces East, he is now facing West.

He then turns to his right and walks 50 meters. Since he was originally facing West and turned right, he is now facing North.

Finally, he turns left and walks another 25 meters. Since he was originally facing North and turned left, he is now facing West again.

So from his starting point at the back of his house, the man has walked in a rectangular path and ended up to the North-West of where he started. So the correct answer is (d) North-west.

Q. A man walks down the backside of his house straight 25 meters, then turns to the right and walks 50 meters again; then he turns towards left and again walks 25 meters. If his house faces to the East, what is his direction from the starting point?  Read More »

Q. Two Statements S1 and S2 are given below with regard to two numbers followed by a Question:  S1: Their product is 21.  S2: Their sum is 10. 

Q. Two Statements S1 and S2 are given below with regard to two numbers followed by a Question:
S1: Their product is 21.
S2: Their sum is 10.

Question: What are the two numbers?
Which one of the following is correct in respect of the above Statements and the Question?
(a) S1 alone is sufficient to answer the Question.
(b) S2 alone is sufficient to answer the Question.
(c) S1 and S2 together are sufficient to answer the Question, but neither S1 alone nor S2 alone is sufficient to answer the Question.
(d) S1 and S2 together are not sufficient to answer the Question.
Correct Answer: (c) S1 and S2 together are sufficient to answer the Question, but neither S1 alone nor S2 alone is sufficient to answer the Question.

Question from UPSC Prelims 2020 CSAT Paper

Explanation :

Product & Sum of two numbers

Let the two numbers be x and y. Then, we have:

S1: xy = 21
S2: x + y = 10

From statement S1, we can express one of the variables in terms of the other. For example, we can write y = 21/x. Substituting this value of y in statement S2, we get:

x + 21/x = 10

Multiplying both sides by x, we get:

x^2 + 21 = 10x

Bringing all the terms to one side, we get:

x^2 – 10x + 21 = 0

This is a quadratic equation that can be factored as (x – 7)(x – 3) = 0. Therefore, the two values of x that satisfy this equation are 7 and 3.

Using statement S1, we can find the corresponding values of y as follows:

If x = 7, then y = 21/x = 3.
If x = 3, then y = 21/x = 7.

Hence, the two numbers that satisfy both statements are 3 and 7. Therefore, the correct answer is (c) S1 and S2 together are sufficient to answer the Question, but neither S1 alone nor S2 alone is sufficient to answer the Question.

Q. Two Statements S1 and S2 are given below with regard to two numbers followed by a Question:  S1: Their product is 21.  S2: Their sum is 10.  Read More »

Q.Two Statements S1 and S2 are given below followed by a Question:  S1: n is a prime number.  S2: n leaves a remainder of 1 when divided by 4. 

Q.Two Statements S1 and S2 are given below followed by a Question:
S1: n is a prime number.
S2: n leaves a remainder of 1 when divided by 4.

Question: If n is a unique natural number between 10 and 20, then what is n?
Which one of the following is correct in respect of the above the Statements and Question?
(a) S1 alone is sufficient to answer the Question.
(b) S2 alone is sufficient to answer the Question.
(c) S1 and S2 together are sufficient to answer the Question, but neither S1 alone nor S2 alone is sufficient to answer the Question.
(d) S1 and S2 together are not sufficient to answer the Question.
Correct Answer: (d) S1 and S2 together are not sufficient to answer the Question.

Question from UPSC Prelims 2020 CSAT Paper

Explanation : 

Let’s consider statement S2 first. If n leaves a remainder of 1 when divided by 4, then n must be of the form 4k + 1, where k is an integer.

Let’s list down the numbers between 10 and 20 that are of the form 4k + 1:
11, 13, 15, 17, 19

Out of these numbers, only 11 and 17 are prime. So, if we consider statement S1 alone, we get two possible values of n, i.e., 11 and 17.

However, if we consider both statements S1 and S2 together, we cannot determine the unique value of n. Both 11 and 17 satisfy both statements S1 and S2. Hence, the correct answer is (d) S1 and S2 together are not sufficient to answer the Question.

Q.Two Statements S1 and S2 are given below followed by a Question:  S1: n is a prime number.  S2: n leaves a remainder of 1 when divided by 4.  Read More »

Q. Two Statements S1 and S2 are given below with regard to four numbers P, Q, R and S followed by a Question:  S1: R is greater-than P as well as Q.  S2: S is not the largest one. 

Q. Two Statements S1 and S2 are given below with regard to four numbers P, Q, R and S followed by a Question:
S1: R is greater-than P as well as Q.
S2: S is not the largest one.

Among four numbers P, Q, R and S which one is the largest?
Which one of the following is correct in respect of the above Statements and the Question?
(a) S1 alone is sufficient to answer the Question.
(b) S2 alone is sufficient to answer the Question.
(c) S1 and S2 together are sufficient to answer the Question, but neither S1 alone nor S2 alone is sufficient to answer the Question.
(d) S1 and S2 together are not sufficient to answer the Question.
Correct Answer: (c) S1 and S2 together are sufficient to answer the Question, but neither S1 alone nor S2 alone is sufficient to answer the Question.

Question from UPSC Prelims 2020 CSAT Paper

Explanation : 

First, let’s consider S1. It tells us that R is greater than both P and Q. However, this statement alone does not provide us with enough information to determine which of the four numbers is the largest, as R could be either the largest or the second-largest number.

Next, let’s consider S2. It tells us that S is not the largest number. This statement is also not sufficient on its own to determine which of the four numbers is the largest, as S could be either the second-largest, third-largest, or smallest number.

However, if we combine both statements, we can deduce that either R is the largest number.
Therefore, the correct answer is (c) S1 and S2 together are sufficient to answer the Question, but neither S1 alone nor S2 alone is sufficient to answer the Question.

Q. Two Statements S1 and S2 are given below with regard to four numbers P, Q, R and S followed by a Question:  S1: R is greater-than P as well as Q.  S2: S is not the largest one.  Read More »

Q. If in a particular year 12th January is a Sunday, then which one of the following is correct? 

Q. If in a particular year 12th January is a Sunday, then which one of the following is correct?

(a) 15th July is a Sunday if the year is a leap year.
(b) 15th July is a Sunday if the year is not a leap year.
(c) 12th July is a Sunday if the year is a leap year.
(d) 12th July is not a Sunday if the year is a leap year.
Correct Answer: (c) 12th July is a Sunday if the year is a leap year.

Question from UPSC Prelims 2020 CSAT Paper

Explanation : 

12th January is a Sunday

No. of days in February is 29 if it is a leap year.

No. of days left in January = 31 – 12 = 19

Total no. of days till 12th July = (19 + 29 + 31 + 30 + 31 + 30 + 12) = 182

No. of odd days = 182 ÷ 7 = 26 weeks and 0 odd days.

So, 12th July is a Sunday if the year is a leap year.

Q. If in a particular year 12th January is a Sunday, then which one of the following is correct?  Read More »

Q. A family of two generations consisting of six members P, Q, R, S, T and U has three males and three females.

Q. A family of two generations consisting of six members P, Q, R, S, T and U has three males and three females.

There are two married couples and two unmarried siblings. U is P ‘s daughter and Q is R ‘s mother – in – law. T is an unmarried male and S is a male. Which one of the following is correct?
(a) R is U’s husband.
(b) R is S’s wife.
(c) S is unmarried.
(d) None of the above
Correct Answer: (b) R is S’s wife.

Question from UPSC Prelims 2020 CSAT Paper

Explanation : 

Family of two generations

From the given information, we know that U is P’s daughter and Q is R’s mother-in-law. This means that R is married to one of Q’s children.
We also know that T is an unmarried male and S is a male. Since there are two married couples in the family and T is unmarried, S must be married.
Since R is married to one of Q’s children and S is married, it follows that R must be married to S. Therefore, (b) R is S’s wife.

Q. A family of two generations consisting of six members P, Q, R, S, T and U has three males and three females. Read More »