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# How to Prepare Arithmetic for OSSSC LSI, Forester, Forest Guard?

Competitive exams such as those conducted by the Odisha Sub-ordinate Staff Selection Commission (OSSSC) for positions like LSI (Livestock Inspector), Forester, and Forest Guard often include a significant portion dedicated to Arithmetic. To excel in these exams, it is crucial to have a solid understanding of various arithmetic topics. Let’s delve into some key arithmetic topics and work through examples to enhance your preparation.

## Understanding OSSSC LSI, Forester, FG Arithmetic Syllabus

• Understanding the exam syllabus for the Arithmetic language component in the OSSSC LSI, Forester, FG Recruitment is essential to plan your preparation effectively.
• Begin by thoroughly understanding the Arithmetic syllabus for the recruitment exam. This will help you identify the specific topics and areas you need to focus on.
• Here’s a breakdown of the key topics typically included in the syllabus:
 Subject Topic Arithmetic SI and Compound Interest Volumes Odd Man Out Quadratic Equations Probability Time and Work Partnership Ratio and Proportion Boats and Streams Simple Interest Time and Distance Problems on Trains Areas Races and Games Numbers and Ages Mixtures and Allegations Mensuration Permutations and Combinations Problems on L.C.M and H.C.F Pipes and Cisterns Percentages Simple Equations Problems on Numbers Averages Indices and Surds Profit and Loss Simplification and Approximation

## Understanding OSSSC LSI, Forester, FG Arithmetic Exam Pattern

•  The written test for LSI, Forester, FG consists of objective-type multiple-choice questions only.
• This exam has negative marking, with a penalty of 0.25 marks for each wrong answer in the written test.
• OSSSC LSI, Forester, and Forest Guard Exam Pattern 2023: The OSSSC LSI, Forester, and Forest Guard written exam will consist of multiple choice questions.
• The total duration of the written test will be 2 1/2 hours and the maximum marks will be 150.
 Post Name Full Marks No. Of Questions No. Of Questions in Arithmetic LSI, Forester, FG 150 150 25

## General Tips:

• Maintain a consistent study schedule.
• Stay disciplined and avoid procrastination.
• Take short breaks during study sessions to stay refreshed.
• Keep a positive attitude and stay confident in your abilities.

### 1. Simple Interest:

Question 1: If the principal is Rs. 2000, the rate of interest is 4% per annum, and the time is 3 years, what is the simple interest?

A. Rs. 240
B. Rs. 250
C. Rs. 260
D. Rs. 270

Solution 1:

The formula for calculating Simple Interest (SI) is:

where:

Given the values:

• Principal () = Rs. 2000,
• Rate of Interest () = 4% per annum,
• Time () = 3 years.

Substitute these values into the formula:

Calculate the result: =(2000×4×3)/100

Therefore, the Simple Interest (SI) on a principal of Rs. 2000 at a rate of 4% per annum for 3 years is Rs. 240.

Question 2: A sum of Rs. 3000 is invested at an interest rate of 6% per annum. Find the simple interest after 2 years.

A. Rs. 300
B. Rs. 330
C. Rs. 360
D. Rs. 380

Solution 2:

The formula for calculating Simple Interest (SI) is:

where:

Given the values:

• Principal () = Rs. 3000,
• Rate of Interest () = 6% per annum,
• Time () = 2 years.

Substitute these values into the formula:

Calculate the result:

(3000×6×2)/100

Therefore, the Simple Interest (SI) on a principal of Rs. 3000 at a rate of 6% per annum for 2 years is Rs. 360.

### 2. Compound Interest:

Question 3: Calculate the compound interest on Rs. 5000 at an annual rate of 8%, compounded annually for 2 years.

A. Rs. 820
B. Rs. 840
C. Rs. 860
D. Rs. 880

Solution 3:

The formula for calculating Compound Interest (CI) is given by:

A= P(1+r/100)^t

where:

• is the principal amount,
• is the rate of interest per annum,
• is the time in years, and
• is the amount after years.

The Compound Interest () is then calculated as:

Given the values:

• Principal () = Rs. 5000,
• Rate of Interest () = 8% per annum,
• Time () = 2 years.

Substitute these values into the formula to find the amount after 2 years ():

=5000(1+8/100)^2

≈5832

Now, calculate the Compound Interest ():

=5832−5000

Therefore, the Compound Interest (CI) on Rs. 5000 at an annual rate of 8%, compounded annually for 2 years, is Rs. 832.

Question 4: If the compound interest on a sum of money is Rs. 1200 at an annual rate of 10%, find the principal amount. The interest is compounded annually for 3 years.

A. Rs. 3000
B. Rs. 4000
C. Rs. 5000
D. Rs. 6000

Solution 4:

• Rate of Interest () = 10% per annum,
• Time () = 3 years.

We need to find the Principal (). Rearrange the formula to solve for :

A= P(1+r/100)^t

Substitute the values into the formula:

=1200(1+10/100)^3

=

Therefore, the principal amount is approximately Rs. 902.98.

### 3. Ratio and Proportion:

Question 5: If the ratio of the lengths of two sides of a rectangle is 2:5 and the perimeter is 70 cm, what is the length of the longer side?

A. 25 cm
B. 30 cm
C. 35 cm
D. 40 cm

Solution 5:

Let the sides be 2x and 5x.

The perimeter () of a rectangle is given by the formula:

In this case, the perimeter is given as 70 cm:

70=2×(l+b)

Simplifying this equation, we find:

Solving for :

Now, we can find the length of the longer side ():

Length of the longer side=5×5=25 cm

So, option A. 25 cm is the correct answer.

Question 6: If 20% of a number is equal to 25, what is 30% of that number?

A. 37.5
B. 45
C. 50
D. 55

Solution 6:

Let the number be .
20/100(x)=25

x=25*100/20=37.5

### 4. Time and Work:

Question 7: A can complete a work in 15 days, and B can complete the same work in 20 days. In how many days will they together complete the work?

A. 6
B. 8
C. 10
D. 12

Solution 7:

Work done by A in 1 day=1/15

Work done by B in 1 day=1/20

Work done by A and B in 1 day=1/15+1/20=4/60=1/15

Days

15

Question 8: A pipe can fill a tank in 6 hours, and another pipe can empty the tank in 8 hours. If both pipes are opened together, how long will it take to fill the tank?

A. 4 hours
B. 5 hours
C. 6 hours
D. 7 hours

Solution 8: Rate of filling of the first pipe=1/6

Rate of emptying of the second pipe=1/8

Net rate when both pipes are opened together=1/6−1/8=1/24

Time to fill the tank=1

Net rate=24

### 5. Ages:

Question 9: The sum of the ages of A and B is 45 years. If A is 15 years older than B, what is the age of B?

A. 15 years
B. 20 years
C. 25 years
D. 30 years

Solution 9: Let the age of B be .

Let’s denote the age of B as . Since A is 15 years older than B,

the age of A is x+15.

The sum of their ages is given as 45 years:

Combine like terms:

2x+15=45

Subtract 15 from both sides:

Divide both sides by 2:

So, the age of B () is 15 years.

Question 10:The present ages of A, B, and C are in the ratio 5:7:9. If the sum of their ages is 105 years, what is C’s present age?

A. 27 years
B. 36 years
C. 45 years
D. 54 years

Solution 10:

Let’s denote the common ratio as . The present ages of A, B, and C can then be expressed as 5, 7, and 9 respectively.

The sum of their ages is given as 105 years:

Combine like terms:

21x=105

Now that we know , we can find the age of C ():

Age of C=9×5=45

So, C’s present age is 45 years.