CSAT 2023

Q. What is the remainder when 85 x 87 x 89 x 91 x 95 x 96 is divided by 100?

Q. What is the remainder when
85 x 87 x 89 x 91 x 95 x 96 is divided by 100?

(a) 0
(b) 1
(c) 2
(d) 4
Correct Answer: (a) 0

Question from UPSC Prelims 2023 CSAT

Explanation : 

Remainder Calculation

The factorization of 100 is 4 x 5^2.

If we look at the given numbers, we can see that 85, 95 each contain a factor of 5, and 96 contain a factor of 4.

Therefore, we can say that the product of these numbers contains at least 4 x 5^2 = 100 as a factor.

This means that when the product of these numbers is divided by 100, the remainder will be 0.

So, the correct answer is (a) 0.

Q. What is the remainder when 85 x 87 x 89 x 91 x 95 x 96 is divided by 100? Read More »

Q. There are four letters and four envelopes and exactly one letter is to be put in exactly one envelope with the correct address. If the letters are randomly inserted into the envelopes, then consider the following statements:

Q. There are four letters and four envelopes and exactly one letter is to be put in exactly one envelope with the correct address. If the letters are randomly inserted into the envelopes, then consider the following statements:

1. It is possible that exactly one letter goes into an incorrect envelope.
2. There are only six ways in which only two letters can go into the correct envelopes.
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: (b) 2 only

Question from UPSC Prelims 2023 CSAT

Explanation : 

The first statement is incorrect.

If we have four letters and four envelopes, and we place one letter correctly, then we have three letters and three envelopes left.

If we now place another letter correctly, we would have two letters and two envelopes left, which means either both of these would be correct or both would be incorrect. If we place one of these two letters incorrectly, the last letter would also have to go into the incorrect envelope because there’s only one choice left. Therefore, it’s not possible to have exactly one letter in an incorrect envelope. The possible scenarios are 0, 2, or 4 letters in the correct envelopes.

The second statement is correct.

There are indeed six ways in which only two letters can go into the correct envelopes.

This can be calculated using the combination formula 4C2 (which stands for “”4 choose 2″”), which gives us the number of ways to choose 2 items from a set of 4. The formula is 4! / (2!(4-2)!) = 6.
So, the correct answer is (b) 2 only.

Q. There are four letters and four envelopes and exactly one letter is to be put in exactly one envelope with the correct address. If the letters are randomly inserted into the envelopes, then consider the following statements: Read More »

Q. AB and CD are 2-digit numbers. Multiplying AB with CD results in a 3-digit number DEF. Adding DEF to another 3-digit number GHI results in 975. Further A, B, C, D, E, F, G, H, I are distinct digits. If E = 0, F = 8, then what is A+B+C equal to ?

Q. AB and CD are 2-digit numbers. Multiplying AB with CD results in a 3-digit number DEF. Adding DEF to another 3-digit number GHI results in 975. Further A, B, C, D, E, F, G, H, I are distinct digits. If E = 0, F = 8, then what is A+B+C equal to ?

(a) 6
(b) 7
(c) 8
(d) 9
Correct Answer: (a) 6

Question from UPSC Prelims 2023 CSAT

Explanation : 

Since E = 0 and F = 8, the product of AB and CD must be a number in the form of 08X, where X is a digit from 1 to 9.

The only way to get a product of 08X is if one of the numbers (AB or CD) is a multiple of 4 and the other number ends with 2 or 7.

The possible pairs of numbers are (12, 34), (17, 24), (24, 17), (34, 12).

However, since the sum of DEF and GHI is 975, the sum of the digits D, G, H, I must be 9 (since E = 0 and F = 8).

The only pair of numbers that satisfies this condition is (12, 34), which gives a product of 408.

Therefore, A = 1, B = 2, C = 3, D = 4.

So, A + B + C = 1 + 2 + 3 = 6.

Therefore, the correct answer is (a) 6.

Q. AB and CD are 2-digit numbers. Multiplying AB with CD results in a 3-digit number DEF. Adding DEF to another 3-digit number GHI results in 975. Further A, B, C, D, E, F, G, H, I are distinct digits. If E = 0, F = 8, then what is A+B+C equal to ? Read More »

Q. What is the remainder if 2^192 is divided by 6?

Q. What is the remainder if 2^192 is divided by 6?

(a) 0
(b) 1
(c) 2
(d) 4
Correct Answer: (d) 4

Question from UPSC Prelims 2023 CSAT

Explanation : 

The powers of 2 cycle in a pattern of 4 when divided by 6.

Specifically, the remainders are 2, 4, 2, 0, 2, 4, 2, 0, and so on. This pattern repeats every 4 powers.

Since 192 is a multiple of 4, the remainder when 2^192 is divided by 6 is the same as the remainder when 2^4 is divided by 6, which is 4.

So, the answer is (d) 4.

Q. What is the remainder if 2^192 is divided by 6? Read More »

Q. A flag has to be designed with 4 horizontal stripes using some or all of the colours red, green and yellow. What is the number of different ways in which this can be done so that no two adjacent stripes have the same colour?

Q. A flag has to be designed with 4 horizontal stripes using some or all of the colours red, green and yellow. What is the number of different ways in which this can be done so that no two adjacent stripes have the same colour?

(a) 12
(b) 18
(c) 24
(d) 36
Correct Answer: (c) 24

Question from UPSC Prelims 2023 CSAT

Explanation : 

Flag with 4 horizontal stripes

A flag has to be designed with 4 horizontal stripes

The first stripe can be any one of the 3 colours, so there are 3 options for the first stripe.

For the second stripe, it cannot be the same colour as the first stripe, so there are only 2 options.

Similarly, for the third and fourth stripes, they cannot be the same colour as the stripe before them, so there are 2 options for each of them.

Therefore, the total number of different ways to design the flag is 3 * 2 * 2 * 2 = 24.

Q. A flag has to be designed with 4 horizontal stripes using some or all of the colours red, green and yellow. What is the number of different ways in which this can be done so that no two adjacent stripes have the same colour? Read More »

Q. Question: Is (p+q-r) greater than (p-q+r), where p, q and r are integers ? Statement-1: (p-q) is positive. Statement-2: (p-r) is negative.

Q. Question: Is (p+q-r) greater than (p-q+r), where p, q and r are integers ?
Statement-1: (p-q) is positive.
Statement-2: (p-r) is negative.

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 2023 CSAT

Explanation : 

From the given question, we need to find whether (p+q-r) is greater than (p-q+r) or not.

Is (p+q-r) greater than (p-q+r), where p, q and r are integers ?

If we simplify this, we get 2q > 2r or q > r. So, we need to determine whether q is greater than r or not.

Statement-1: (p-q) is positive. This means p > q. But this statement doesn’t give any information about r. So, we cannot answer the question using this statement alone.

Statement-2: (p-r) is negative. This means p < r. But this statement doesn’t give any information about q. So, we cannot answer the question using this statement alone.

Using both the statements together, we know that p > q and p < r. This implies that r > p > q or r > q. So, q is not greater than r. Therefore, (p+q-r) is not greater than (p-q+r).

So, the correct answer is (c) The Question can be answered by using both the Statements together, but cannot be answered using either Statement alone.

Q. Question: Is (p+q-r) greater than (p-q+r), where p, q and r are integers ? Statement-1: (p-q) is positive. Statement-2: (p-r) is negative. Read More »

Q. Question: Is p greater than q? Statement-1: p x q is greater than zero. Statement-2: p^2 is greater than q^2.

Q. Question: Is p greater than q?
Statement-1: p x q is greater than zero.
Statement-2: p^2 is greater than q^2.

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 2023 CSAT

Explanation : 

Question – Is p greater than q?

Statement-1: p x q is greater than zero. This statement implies that both p and q are either positive or negative. However, it does not provide information about whether p is greater than q.

Statement-2: p^2 is greater than q^2. This statement implies that the absolute value of p is greater than the absolute value of q. However, it does not provide information about whether p is greater than q, because both p and q could be negative.

Even if we use both statements together, we cannot definitively answer whether p is greater than q. For example, if p and q are both positive and p^2 is greater than q^2, then p is greater than q. But if p and q are both negative and p^2 is greater than q^2, then p is actually less than q.

Therefore, the correct answer is (d) The Question cannot be answered even by using both the Statements together.

Q. Question: Is p greater than q? Statement-1: p x q is greater than zero. Statement-2: p^2 is greater than q^2. Read More »

Q. What is the sum of all 4-digit numbers less than 2000 formed by the digits 1, 2, 3 and 4, where none of the digits is repeated?

Q. What is the sum of all 4-digit numbers less than 2000 formed by the digits 1, 2, 3 and 4, where none of the digits is repeated?

(a) 7998
(b) 8028
(c) 8878
(d) 9238
Correct Answer: (a) 7998

Question from UPSC Prelims 2023 CSAT

Explanation : 

4-Digit Numbers Sum

The 4-digit numbers less than 2000 formed by the digits 1, 2, 3, and 4 where none of the digits is repeated are 1234, 1243, 1324, 1342, 1423, and 1432.

Adding these numbers together gives the sum:

1234 + 1243 + 1324 + 1342 + 1423 + 1432 = 7998

So, the correct answer is (a) 7998.

Q. What is the sum of all 4-digit numbers less than 2000 formed by the digits 1, 2, 3 and 4, where none of the digits is repeated? Read More »