CSAT 2021

Q. A bank employee drives 10 km towards South from her house and turns to her left and drives another 20 km.

Q. A bank employee drives 10 km towards South from her house and turns to her left and drives another 20 km.

She again turns left and drives 40 km, then she turns to her right and drives for another 5 km. She again turns to her right and drives another 30 km to reach her bank where she works. What is the shortest distance between her bank and her house?

(a) 20 km
(b) 25 km
(c) 30 km
(d) 35 km
Correct Answer: (b) 25 km

Question from UPSC Prelims 2021 CSAT Paper

Explanation : 

A bank employee drives 10 km south

Starting point: (0,0) – House

Movement sequence:
1. South 10 km → (0, -10)
2. Left turn, East 20 km → (20, -10)
3. Left turn, North 40 km → (20, 30)
4. Right turn, East 5 km → (25, 30)
5. Right turn, South 30 km → (25, 0) – Bank

Shortest distance calculation:
– Using Pythagorean theorem
– Distance = √[(x₂-x₁)² + (y₂-y₁)²]
– Distance = √[(25-0)² + (0-0)²]
– Distance = √(625 + 0)
– Distance = √625
– Distance = 25 km

Therefore, the shortest distance between her house and bank is 25 kilometers.

A bank employee drives 10 km

Q. A bank employee drives 10 km towards South from her house and turns to her left and drives another 20 km. Read More »

Q. Images of consonants of the English alphabet (Capitals) are observed in a mirror. What is the number of images of these which do not look like their original shapes?

Q. Images of consonants of the English alphabet (Capitals) are observed in a mirror. What is the number of images of these which do not look like their original shapes?

(a) 13
(b) 14
(c) 15
(d) 16
Correct Answer: (b) 14

Question from UPSC Prelims 2021 CSAT Paper

Explanation : 

Mirror images of consonants of the english alphabet

To determine the number of consonant letters in the English alphabet whose mirror images do not resemble their original shapes, follow these steps:

1. Identify the Consonants:

The English alphabet consists of 26 letters. The vowels are A, E, I, O, and U. Sometimes Y is considered a vowel, but typically it’s treated as a consonant in such contexts.
Consonants: B, C, D, F, G, H, J, K, L, M, N, P, Q, R, S, T, V, W, X, Y, Z
Total Consonants: 21

2. Determine Symmetrical Letters:

A letter is considered symmetrical if its mirror image is identical to the original. For capital letters, the following consonants are symmetrical:

– Symmetrical Consonants: H, M, T, V, W, X, Y
Total Symmetrical Consonants: 7

3. Calculate Non-Symmetrical Consonants:

Subtract the number of symmetrical consonants from the total number of consonants to find the number of non-symmetrical consonants.

Non-Symmetrical Consonants: 21 (total) – 7 (symmetrical) = 14
Answer: (b) 14

Q. Images of consonants of the English alphabet (Capitals) are observed in a mirror. What is the number of images of these which do not look like their original shapes? Read More »

Statement: Some cats are almirahs. Some almirahs are chairs. All chairs are tables.

Statement: Some cats are almirahs. Some almirahs are chairs. All chairs are tables.

Conclusion-I: Certainly some almirahs are tables.
Conclusion-II: Some cats may not be chairs.

Which one of the following is correct?
(a) Only Conclusion-I
(b) Only Conclusion-II
(c) Both Conclusion-I and Conclusion-II
(d) Neither Conclusion-I nor Conclusion-II
Correct Answer: (c) Both Conclusion-I and Conclusion-II

Question from UPSC Prelims 2021 CSAT Paper

Explanation :

Some cats are almirahs

Conclusions from Cat, Almirah, Chair Statement

Given Statements:
1. Some cats are almirahs
2. Some almirahs are chairs
3. All chairs are tables

Let’s analyze each conclusion:

Conclusion I: “Some almirahs are tables”

– Some almirahs are chairs (given)
– All chairs are tables (given)
– Therefore, those almirahs that are chairs must also be tables
– This makes Conclusion I logically valid

Conclusion II: “Some cats may not be chairs”

– Some cats are almirahs (given)
– Some almirahs are chairs (given)
– We don’t know if ALL cats are almirahs
– We don’t know if ALL almirahs are chairs
– Therefore, it’s possible that some cats may not be chairs
– This makes Conclusion II logically valid

Answer: Both conclusions I and II logically follow from the given statements.

Statement: Some cats are almirahs. Some almirahs are chairs. All chairs are tables. Read More »

Q. A person X from a place A and another person Y from a place B set out at the same time to walk towards each other.

Q. A person X from a place A and another person Y from a place B set out at the same time to walk towards each other.

The places are separated by a distance of 15 km. X walks with a uniform speed of 1.5 km/hr and Y walks with a uniform speed of 1 km/hr in the first hour, with a uniform speed of 1.25 km/hr in the second hour and with a uniform speed of 1.5 km/hr in the third hour and so on.

Which of the following is/are correct?
1. They take 5 hours to meet.
2. They meet midway between A and B.
Select the correct answer using the code given below:
(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2
Correct Answer: (c) Both 1 and 2

Question from UPSC Prelims 2021 CSAT Paper

Explanation : 

A person X from place a & other Y from B

Given information:
– Total distance between A and B = 15 km
– Person X’s speed = constant 1.5 km/hr
– Person Y’s speed increases by 0.25 km/hr every hour:
Hour 1: 1.0 km/hr
Hour 2: 1.25 km/hr
Hour 3: 1.5 km/hr
Hour 4: 1.75 km/hr
Hour 5: 2.0 km/hr

Step 1: Calculate X’s distance in 5 hours
– X’s distance = Speed × Time
– X’s distance = 1.5 × 5 = 7.5 km

Step 2: Calculate Y’s total distance in 5 hours
– Hour 1: 1.0 km
– Hour 2: 1.25 km
– Hour 3: 1.5 km
– Hour 4: 1.75 km
– Hour 5: 2.0 km
Total = 7.5 km

Step 3: Verify statements
1. They take 5 hours to meet
– Total distance covered = X’s distance + Y’s distance
– 7.5 + 7.5 = 15 km (complete distance)
– Therefore, they meet in 5 hours (True)

2. They meet midway
– Both cover 7.5 km each
– 7.5 km is exactly half of 15 km
– Therefore, they meet midway (True)

Answer: Option (c) Both statements 1 and 2 are correct.

Q. A person X from a place A and another person Y from a place B set out at the same time to walk towards each other. Read More »

Q. You are given two identical sequences in two rows: Sequence-I: 8 4 6 15 52.5 236.5 Sequence-II: 5 A B C D E

Q. You are given two identical sequences in two rows:

Sequence-I: 8 4 6 15 52.5 236.5
Sequence-II: 5 A B C D E

What is the entry in the place of C for the Sequence-II?
(a) 2.5
(b) 5
(c) 9.375
(d) 32.8125
Correct Answer: (c) 9.375

Question from UPSC Prelims 2021 CSAT Paper

Explanation : 

8 4 6 15 x 236.25

Let us solve this step by step:

Sequence I:
Let us start with 8:
8 × 0.5 → 4
4 × 1.5 → 6
6 × 2.5 → 15
15 × 3.5 → 52.5
52.5 × 4.5 → 236.25

Sequence II:
Let us start with 5:
5 × 0.5 → 2.5 (A)
2.5 × 1.5 → 3.75 (B)
3.75 × 2.5 → 9.375 (C)

Let us observe the pattern:
The multipliers increase by 1 each time:
0.5, 1.5, 2.5, 3.5, 4.5

Q. You are given two identical sequences in two rows: Sequence-I: 8 4 6 15 52.5 236.5 Sequence-II: 5 A B C D E Read More »

Q. Following is a matrix of certain entries. The entries follow a certain trend row-wise. Choose the missing entry (?) accordingly.

Q. Following is a matrix of certain entries. The entries follow a certain trend row-wise. Choose the missing entry (?) accordingly.

7B 10A 3C
3C 9B 6A
10A 13C ?

(a) 9B
(b) 3A
(c) 3B
(d) 3C
Correct Answer: (c) 3B

Question from UPSC Prelims 2021 CSAT Paper

Explanation : 

7b 10a 3c

Row 1 : 10 – 7 = 3
Row 2 : 9 – 3 = 3
Row 3 = 13 – 10 = 3, B was missing in row 3

Q. Following is a matrix of certain entries. The entries follow a certain trend row-wise. Choose the missing entry (?) accordingly. Read More »

Q. What is the value of ‘X’ in the sequence 2, 7, 22, 67, 202, X, 1822?

Q. What is the value of ‘X’ in the sequence 2, 7, 22, 67, 202, X, 1822?

(a) 603
(b) 605
(c) 607
(d) 608
Correct Answer: (c) 607

Question from UPSC Prelims 2021 CSAT Paper

Explanation : 

Given sequence: 2, 7, 22, 67, 202, X, 1822

Pattern: Each number is generated by multiplying the previous number by 3 and adding 1.

Let’s verify each step:
2 → 7: 2 × 3 + 1 = 7
7 → 22: 7 × 3 + 1 = 22
22 → 67: 22 × 3 + 1 = 67
67 → 202: 67 × 3 + 1 = 202
202 → X: 202 × 3 + 1 = 607
607 → 1822: 607 × 3 + 1 = 1822

Answer: X = 607

Q. What is the value of ‘X’ in the sequence 2, 7, 22, 67, 202, X, 1822? Read More »

Q. Replace the incorrect term by the correct term in the given sequence

Q. Replace the incorrect term by the correct term in the given sequence

3, 2, 7, 4, 13, 10, 21, 18, 31, 28, 43, 40
where odd terms and even terms follow the same pattern.

(a) 0
(b) 1
(c) 3
(d) 6
Correct Answer: (a) 0

Question from UPSC Prelims 2021 CSAT Paper

Explanation :

Replacing the incorrect term by correct term

Let’s solve this sequence problem step by step:

1. Original sequence:
3, 2, 7, 4, 13, 10, 21, 18, 31, 28, 43, 40

2. Analysis of odd-positioned numbers (1st, 3rd, 5th…):
3, 7, 13, 21, 31, 43
Differences: 4, 6, 8, 10, 12
Pattern: Each difference increases by 2

3. Analysis of even-positioned numbers (2nd, 4th, 6th…):
2, 4, 10, 18, 28, 40
Differences: 2, 6, 8, 10, 12
Problem: First difference is 2, breaking the pattern

4. Correction needed:
Starting from 3 (first number)
For consistent pattern, next number should create difference of 4
Therefore, second number should be 0 (not 2)
Because: 3 → 0 gives difference of 3
And: 0 → 4 gives difference of 4

5. After correction:
Odd terms differences: 4, 6, 8, 10, 12
Even terms differences: 4, 6, 8, 10, 12

Answer: (a) 0 is correct.

The sequence becomes perfect when 2 is replaced with 0, making both odd and even terms follow same pattern of differences increasing by 2.

Q. Replace the incorrect term by the correct term in the given sequence Read More »

Q. Seven books P, Q, R, S, T, U and V are placed side by side. R, Q and T have blue covers and other books have red covers. Only S and U are new books and the rest are old. P, R and S are law reports; the rest are Gazetteers. Books of old Gazetteers with blue covers are

Q. Seven books P, Q, R, S, T, U and V are placed side by side. R, Q and T have blue covers and other books have red covers. Only S and U are new books and the rest are old. P, R and S are law reports; the rest are Gazetteers. Books of old Gazetteers with blue covers are

(a) Q and R
(b) Q and U
(c) Q and T
(d) T and U
Correct Answer: (c) Q and T

Question from UPSC Prelims 2021 CSAT Paper

Explanation : 

Seven Book P, Q, R, S, T, U & V Arrangement

From the given information, we know that R, Q and T have blue covers and other books have red covers. We also know that only S and U are new books and the rest are old. Finally, we know that P, R and S are law reports; the rest are Gazetteers.

Based on this information, we can conclude that Q and T are old Gazetteers with blue covers. This is because they both have blue covers (as stated in the first sentence), they are both old (since only S and U are new), and they are both Gazetteers (since P, R and S are law reports).

seven books

Q. Seven books P, Q, R, S, T, U and V are placed side by side. R, Q and T have blue covers and other books have red covers. Only S and U are new books and the rest are old. P, R and S are law reports; the rest are Gazetteers. Books of old Gazetteers with blue covers are Read More »

Q. In the English alphabet, the first 4 letters are written in opposite order, and the next 4 letters are written in opposite order and so on; and at the end Y and Z are interchanged. Which will be the fourth letter to the right of the 13th letter?

Q. In the English alphabet, the first 4 letters are written in opposite order, and the next 4 letters are written in opposite order and so on; and at the end Y and Z are interchanged. Which will be the fourth letter to the right of the 13th letter?

(a) N
(b) T
(c) H
(d) I
Correct Answer: (b) T

Question from UPSC Prelims 2021 CSAT Paper

Explanation : 

Arrangement of English Alphabet

The English alphabet is: ABCD EFGH IJKL MNOP QRST UVWX YZ

As per the question, the letters are arranged as follows:

DCBA HGFE LKJI PONM TSRQ XWVU ZY

The 13th letter in this arrangement is P.

The 4th letter to its right is T.

english alphabet the first 4 letters

Q. In the English alphabet, the first 4 letters are written in opposite order, and the next 4 letters are written in opposite order and so on; and at the end Y and Z are interchanged. Which will be the fourth letter to the right of the 13th letter? Read More »