Competitive exams such as those conducted by the Odisha Subordinate 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 

Understanding OSSSC LSI, Forester, FG Arithmetic Exam Pattern
 The written test for LSI, Forester, FG consists of objectivetype multiplechoice 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:
Correct Answer: A. Rs. 240
The formula for calculating Simple Interest (SI) is:
$SI=(P×R×T)/100 $
where:
Given the values:
 Principal ($P$) = Rs. 2000,
 Rate of Interest ($R$) = 4% per annum,
 Time ($T$) = 3 years.
Substitute these values into the formula:
Calculate the result: =(2000×4×3)/100
$SI=240 $
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:
Correct Answer: C. 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:
Correct Answer: B. Rs. 840
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:
Correct Answer: A. Rs. 3000
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 ($P$) of a rectangle is given by the formula:
$P=2×(Length+Width)$
In this case, the perimeter is given as 70 cm:
70=2×(l+b)
$70/2=2x+5x$
Simplifying this equation, we find:
$35=7x$
$5=x$
Solving for $x$:
$x=5$
Now, we can find the length of the longer side ($5x$):
Length of the longer side=5×5=25 cm
So, option A. 25 cm is the correct answer.
Correct Answer: A. 25 cm
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 $x$.
20/100(x)=25
x=25*100/20=37.5
Correct Answer: A. 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
$Work done by A and B in 1 day=15 $ Days
$Days required to complete the work together$
Correct Answer: A. 6
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
$Net rate when both pipes are opened together $ Time to fill the tank=1
Net rate=24
$Time to fill the tank=24/4$
Correct Answer: C. 6 hours
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 $x$.
Let’s denote the age of B as $x$. 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:
$x+(x+15)=45$
Combine like terms:
2x+15=45
$2x+15=45$
Subtract 15 from both sides:
$2x=30$
Divide both sides by 2:
$x=15$
So, the age of B ($x$) is 15 years.
Correct Answer: A. 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?
Official Links  
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Official website  osssc.gov.in 
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