OPSC OCS Paper 2 2024

Q. A chemist has one solution which is 50% acid and a second which is 25% acid. How much of each should be mixed to make 10 litres of a 40% acid solution?

Q. A chemist has one solution which is 50% acid and a second which is 25% acid. How much of each should be mixed to make 10 litres of a 40% acid solution?

(A) 4 litres of 50% and 6 litres of 25%
(B) 3 litres of 50% and 7 litres of 25%
(C) 6 litres of 50% and 4 litres of 25%
(D) 7 litres of 50% and 3 litres of 25%

Question from Odisha OCS Paper 2 2024

The correct answer is (C) 6 litres of 50% and 4 litres of 25%

Explanation:

To solve this problem, we use the concept of mixture and alligation. Let’s break it down step by step:

Step 1: Define the variables
Let the amount of the 50% acid solution be x litres.
Then, the amount of the 25% acid solution will be (10 – x) litres, since the total mixture is 10 litres.

Step 2: Write the equation for the total acid content
The total acid content in the mixture is given by:
(Acid from 50% solution) + (Acid from 25% solution) = (Acid in 40% solution).

This can be written as:
0.50x + 0.25(10 – x) = 0.40(10)

Step 3: Simplify the equation
Expand and simplify:
0.50x + 2.5 – 0.25x = 4
0.25x + 2.5 = 4
0.25x = 4 – 2.5
0.25x = 1.5
x = 1.5 ÷ 0.25
x = 6

Step 4: Interpret the result
The amount of the 50% acid solution is 6 litres.
The amount of the 25% acid solution is 10 – 6 = 4 litres.

Final Answer: The correct option is (C) 6 litres of 50% and 4 litres of 25%.

Q. A chemist has one solution which is 50% acid and a second which is 25% acid. How much of each should be mixed to make 10 litres of a 40% acid solution? Read More »

Q. Arrange in order, from least to greatest: -8/5, -3/2, -19/11

Q. Arrange in order, from least to greatest: -8/5, -3/2, -19/11

(A) -8/5 < -3/2 < -19/11
(B) -19/11 < -3/2 < -8/5
(C) -19/11 < -8/5 < -3/2
(D) -3/2 < -19/11 < -8/5

Question from Odisha OCS Paper 2 2024

The correct answer is (C) -19/11 < -8/5 < -3/2.

Explanation:

To solve this, we need to compare the given fractions: -8/5, -3/2, and -19/11. Since all the numbers are negative, the smaller the absolute value, the greater the number.

Step 1: Convert all fractions to decimals
-8/5 = -1.6
-3/2 = -1.5
-19/11 = -1.727 (approximately)

Step 2: Compare the decimals
From least to greatest:
The smallest number is -19/11 (-1.727).
The next smallest is -8/5 (-1.6).
The largest is -3/2 (-1.5).

Step 3: Write the order
From least to greatest: -19/11 < -8/5 < -3/2

Final Answer: The correct option is (C) -19/11 < -8/5 < -3/2.

Q. Arrange in order, from least to greatest: -8/5, -3/2, -19/11 Read More »

Q. The probability of getting a bad egg in a lot of 400 eggs is 0.035. The number of bad eggs in the lot is

Q. The probability of getting a bad egg in a lot of 400 eggs is 0.035. The number of bad eggs in the lot is

(A) 7
(B) 14
(C) 21
(D) 28

Question from Odisha OCS Paper 2 2024

The correct answer is (B) 14.

Explanation:

To solve this problem, let’s break it down step by step:

Step 1: Understand the given data
The probability of getting a bad egg is 0.035.
The total number of eggs in the lot is 400.

Step 2: Calculate the expected number of bad eggs
The expected number of bad eggs can be calculated as:
Number of bad eggs = Probability of a bad egg × Total number of eggs
Number of bad eggs = 0.035 × 400 = 14.

Final Answer: The correct option is (B) 14.

Q. The probability of getting a bad egg in a lot of 400 eggs is 0.035. The number of bad eggs in the lot is Read More »

Q. Sonia can copy 50 pages in 10 hours. Priya and Sonia can copy 300 pages in 40 hours. Priya can copy 30 pages in

Q. Sonia can copy 50 pages in 10 hours. Priya and Sonia can copy 300 pages in 40 hours. Priya can copy 30 pages in

(A) 10 hours
(B) 11 hours
(C) 12 hours
(D) 13 hours

Question from Odisha OCS Paper 2 2024

The correct answer is (C) 12 hours.

Explanation:

Step 1: Determine Sonia’s work rate
Sonia can copy 50 pages in 10 hours.
So, Sonia’s work rate is:
Work rate of Sonia = 50 pages ÷ 10 hours = 5 pages per hour.

Step 2: Determine the combined work rate of Sonia and Priya
Sonia and Priya together can copy 300 pages in 40 hours.
So, their combined work rate is:
Combined work rate = 300 pages ÷ 40 hours = 7.5 pages per hour.

Step 3: Determine Priya’s work rate
The combined work rate of Sonia and Priya is 7.5 pages per hour, and Sonia’s work rate is 5 pages per hour.
Thus, Priya’s work rate = Combined work rate – Sonia’s work rate = 7.5 – 5 = 2.5 pages per hour.

Step 4: Time taken by Priya to copy 30 pages
If Priya’s work rate is 2.5 pages per hour, the time taken by Priya to copy 30 pages is:
Time = Work ÷ Work rate = 30 ÷ 2.5 = 12 hours.

Final Answer: The correct option is (C) 12 hours.

Q. Sonia can copy 50 pages in 10 hours. Priya and Sonia can copy 300 pages in 40 hours. Priya can copy 30 pages in Read More »

Q. A can do 3/4 of a work in 12 days. He can complete 1/8 of the work in

Q. A can do 3/4 of a work in 12 days. He can complete 1/8 of the work in

(A) 3 days
(B) 4 days
(C) 72 days
(D) 2 days

Question from Odisha OCS Paper 2 2024

The correct answer is (D) 2 days.

Explanation:

Step 1: Determine A’s work rate
A can complete 3/4 of the work in 12 days.
So, the amount of work A does in 1 day is:
Work rate = (3/4) ÷ 12 = (3/4) × (1/12) = 1/16 of the work per day.

Step 2: Time to complete 1/8 of the work
Now, we need to find how many days A will take to complete 1/8 of the work.
If A completes 1/16 of the work in 1 day, then the time required to complete 1/8 of the work is:
Time = (Work) ÷ (Work rate) = (1/8) ÷ (1/16) = 2 days.

Final Answer: The correct option is (D) 2 days.

Q. A can do 3/4 of a work in 12 days. He can complete 1/8 of the work in Read More »

Q. Find the next number in the sequence 17, 17, 51, 255, 1785

Q. Find the next number in the sequence 17, 17, 51, 255, 1785

(A) 16065
(B) 19635
(C) 15965
(D) 14955

Question from Odisha OCS Paper 2 2024

The correct answer is (A) 16065

Explanation:

To determine the next number in the sequence 17, 17, 51, 255, 1785, let’s analyze the pattern:

1. First to Second Term: 17 to 17 is multiplied by 1.
2. Second to Third Term: 17 × 3 = 51.
3. Third to Fourth Term: 51 × 5 = 255.
4. Fourth to Fifth Term: 255 × 7 = 1785.

Observing the pattern, the multipliers are consecutive odd numbers: 1, 3, 5, 7. Following this pattern, the next multiplier should be 9.

5. Fifth to Sixth Term: 1785 × 9 = 16065.

Q. Find the next number in the sequence 17, 17, 51, 255, 1785 Read More »

Q. A peon purchased a chair for ₹ 700, spent ₹ 170 on its repair and ₹ 30 on the cartage. If he sold the chair for ₹ 1,080, his gain percent is

Q. A peon purchased a chair for ₹ 700, spent ₹ 170 on its repair and ₹ 30 on the cartage. If he sold the chair for ₹ 1,080, his gain percent is

(A) 10
(B) 20
(C) 30
(D) 54.29

Question from Odisha OCS Paper 2 2024

The correct answer is (B) 20

Explanation:

Let’s solve this step by step.

1. First, let’s calculate the total cost for the peon:
Purchase price = ₹ 700
Repair cost = ₹ 170
Cartage cost = ₹ 30
Total cost = 700 + 170 + 30 = ₹ 900

2. Selling price = ₹ 1,080

3. To find gain percent:
Gain = Selling price – Cost price
Gain = 1,080 – 900 = ₹ 180

4. Gain percent = (Gain ÷ Cost price) × 100
= (180 ÷ 900) × 100
= 0.2 × 100
= 20%

Therefore, the gain percent is 20%. The answer is (B) 20.

Q. A peon purchased a chair for ₹ 700, spent ₹ 170 on its repair and ₹ 30 on the cartage. If he sold the chair for ₹ 1,080, his gain percent is Read More »

Q. The sum of squares of two numbers is 146. If the square of their difference is 36, then the product of both the numbers is

Q. The sum of squares of two numbers is 146. If the square of their difference is 36, then the product of both the numbers is

(A) 72
(B) 160
(C) 55
(D) 16

Question from Odisha OCS Paper 2 2024

The correct answer is (C) 55

Explanation:

Let’s solve this step by step.

1) Let’s say the two numbers are x and y

2) Given information:
x² + y² = 146
(x – y)² = 36

3) From (x – y)² = 36:
x² + y² – 2xy = 36

4) From x² + y² = 146:
Substituting this in the above equation
146 – 2xy = 36
-2xy = 36 – 146
-2xy = -110
xy = 55

5) Therefore, the product of both numbers is 55, (C) 55 is the correct answer.

Q. The sum of squares of two numbers is 146. If the square of their difference is 36, then the product of both the numbers is Read More »

Q. 250%/5% = ?

Q. 250%/5% = ?

(A) 50%
(B) 500%
(C) 5000%
(D) 5%

Question from Odisha OCS Paper 2 2024

The correct answer is (C) 5000%

Explanation:

Let’s solve this step by step:

1) When dividing percentages, we can treat them as regular numbers:
250% ÷ 5% = 2.5 ÷ 0.05

2) To divide by a decimal, we can multiply by its reciprocal:
2.5 ÷ 0.05 = 2.5 × (1/0.05) = 2.5 × 20 = 50

3) Since we’re dividing percentages, our answer should be in percentage form:
50 = 5000%

Therefore, the answer is (C) 5000%

Q. 250%/5% = ? Read More »

Q. A sum of ₹ 10,000 is divided into two parts such that one part is invested at 8% per annum and the other at 6% per annum. If the annual interest earned from both investments is ₹ 700, what is the amount invested at 8%?

Q. A sum of ₹ 10,000 is divided into two parts such that one part is invested at 8% per annum and the other at 6% per annum. If the annual interest earned from both investments is ₹ 700, what is the amount invested at 8%?

(A) ₹ 4,000
(B) ₹ 3,000
(C) ₹ 5,000
(D) ₹ 6,000

Question from Odisha OCS Paper 2 2024

The correct answer is (C) ₹5,000

Explanation:

Let’s solve this step by step.

1) Let’s say the amount invested at 8% is x
Then amount invested at 6% = (10,000 – x)

2) Given that total interest = ₹700
Interest from 8% investment = 8% of x = 0.08x
Interest from 6% investment = 6% of (10,000 – x) = 0.06(10,000 – x)

3) We can write the equation:
0.08x + 0.06(10,000 – x) = 700

4) Simplify right side of equation:
0.08x + 600 – 0.06x = 700

5) Combine like terms:
0.02x + 600 = 700
0.02x = 100
x = 5,000

6) Verification:
Amount at 8%: ₹5,000 → Interest = ₹400
Amount at 6%: ₹5,000 → Interest = ₹300
Total interest = ₹700 ✓

Therefore, the amount invested at 8% is ₹5,000.

The answer is (C) ₹5,000.

Q. A sum of ₹ 10,000 is divided into two parts such that one part is invested at 8% per annum and the other at 6% per annum. If the annual interest earned from both investments is ₹ 700, what is the amount invested at 8%? Read More »