SSC CGL JSO Statistics Paper, Most Imp Questions & Topic Weightage

The SSC CGL Junior Statistical Officer (JSO) paper is an important part of Paper II of Tier 2, designed to test a candidate’s understanding of applied statistics and data interpretation. If you’re preparing for SSC CGL Tier 2 (Statistics section), knowing the syllabus, weightage, and key topics is important for scoring high.

SSC CGL JSO Most Important Questions

Statistics is a key section in SSC CGL Junior Statistical Officer Paper 2. Here are 20 most important questions on topics like Central Tendency, Probability, Correlation, Sampling, Time Series, and Inference, designed at Tier 2 difficulty, with answers for quick practice.

Q1. If the mean of 5 numbers is 12 and one number is replaced by 20, the new mean becomes 14. Find the number replaced.
A) 6
B) 8
C) 10
D) 12
Answer: B) 8

Q2. For a continuous random variable X with pdf f(x) = kx² for 0 ≤ x ≤ 2, find k.
A) 1
B) 3/8
C) 2/3
D) 1/4
Answer: B) 3/8

Q3. The coefficient of skewness (Karl Pearson) for a distribution with mean = 50, median = 47, and standard deviation = 4 is:
A) 0.75
B) 0.5
C) 0.25
D) 1
Answer: A) 0.75

Q4. If two variables X and Y have a correlation coefficient of 0.8, then the coefficient of determination is:
A) 0.64
B) 0.80
C) 0.36
D) 0.72
Answer: A) 0.64

Q5. If the variance of X is 16, what is the variance of 3X + 5?
A) 16
B) 48
C) 144
D) 21
Answer: C) 144

Q6. The Spearman’s rank correlation coefficient between two variables with tied ranks can be calculated using:
A) Pearson correlation formula
B) Difference of ranks formula
C) Regression formula
D) None of these
Answer: B) Difference of ranks formula

Q7. In a two-way ANOVA with r = 3 rows and c = 4 columns, the degrees of freedom for interaction is:
A) 6
B) 2
C) 8
D) 1
Answer: A) 6

Q8. A sample of 100 observations has a mean of 50 and SD of 10. The standard error of the mean is:
A) 1
B) 10
C) 0.1
D) 5
Answer: A) 1

Q9. For a binomial distribution with n = 10 and p = 0.5, variance is:
A) 2.5
B) 5
C) 10
D) 1
Answer: A) 2.5

Q10. If the probability of A = 0.4, probability of B = 0.5, and P(A ∩ B) = 0.2, then P(A | B) = ?
A) 0.2
B) 0.4
C) 0.5
D) 0.6
Answer: B) 0.4

SSC CGL Tier 1 Result Out, Check your result Here

Q11. For a binomial distribution with n = 10 and p = 0.5, variance is:
A) 2.5
B) 5
C) 10
D) 1
Answer: A) 2.5

Q12. The probability generating function (PGF) of a Poisson variable with mean λ is:
A) e^(λ(t−1))
B) λ(1 − t)
C) e^(−λt)
D) (1 − p + pt)^n

Answer: A) e^(λ(t−1))

Q13. If Q1 = 20, Q3 = 40, and median = 30, then Bowley’s coefficient of skewness is:
A) 0
B) 0.2
C) 0.25
D) 0.1
Answer: A) 0

Q14. In regression analysis, the sum of residuals is:
A) Equal to 1
B) Equal to zero
C) Positive
D) Negative
Answer: B) Equal to zero

Q15. For a normal distribution N(μ, σ²), the probability that X lies within μ ± 2σ is approximately:
A) 68%
B) 95%
C) 99%
D) 90%

Answer: B) 95%

Q16. For a sample of size n from a population, the unbiased estimator of population variance is:
A) Σ(xi − x̄)^2 / n
B) Σ(xi − x̄)^2 / (n − 1)
C) Σ(xi − x̄)^2 / (n + 1)
D) Σ(xi^2)

Answer: B) Σ(xi − x̄)^2 / (n − 1)

Q17. In a Poisson distribution, the probability of exactly 2 events is 0.224. If the mean is 2, what is P(X = 2) = e^(−λ) * λ² / 2!?

A) 0.224
B) 0.270
C) 0.180
D) 0.250

Answer: A) 0.224

Q18. If a time series has seasonal variation, it can be removed by:
A) Differencing
B) Smoothing
C) Seasonal Index
D) Regression
Answer: C) Seasonal Index

Q19. If population size N = 1000 and sample size n = 100, the sampling fraction is:
A) 1%
B) 10%
C) 50%
D) 100%
Answer: B) 10%

Q20. The Chi-square test is used for:
A) Mean testing
B) Proportion testing
C) Goodness of fit and independence testing
D) Regression
Answer: C) Goodness of fit and independence testing

SSC JSO Topic-wise Weightage (Approximate)

In the SSC CGL/JSO Statistics Paper, different topics carry different marks. Knowing the expected weightage of each topic can help you plan your preparation and focus on high-scoring areas. The table below shows the approximate marks for each important topic in the exam.

Topic	Expected Weightage
Measures of Central Tendency & Dispersion	10-12 marks
Correlation & Regression	10-15 marks
Probability & Probability Distributions	15-20 marks
Sampling Theory	8-10 marks
Statistical Inference	20-25 marks
Time Series & Index Numbers	10-15 marks
Moments, Skewness, Kurtosis	5-8 marks

SSC CGL JSO Statistics Syllabus 2025

The Statistics syllabus according to the SSC JSO Exam Pattern is divided into key topics that test your conceptual clarity and application skills.

Unit	Topic
1. Collection, Classification & Presentation of Statistical Data	Meaning, types of data, primary & secondary data, frequency distribution, tabulation, diagrammatic representation.
2. Measures of Central Tendency	Mean, Median, Mode, Geometric & Harmonic Mean, Weighted Mean.
3. Measures of Dispersion	Range, Quartile Deviation, Mean Deviation, Standard Deviation, Coefficient of Variation.
4. Moments, Skewness & Kurtosis	Types of moments, coefficient of skewness, coefficient of kurtosis, shape of distribution.
5. Correlation & Regression	Scatter diagrams, Karl Pearson’s coefficient, Spearman’s rank correlation, regression lines, multiple correlation.
6. Probability Theory	Basic definitions, addition & multiplication theorems, conditional probability, Bayes’ theorem.
7. Random Variables & Probability Distributions	Random variables, binomial, Poisson, normal, exponential, and joint distributions.
8. Sampling Theory	Population and sample, sampling techniques, errors, sampling distributions, central limit theorem.
9. Statistical Inference	Estimation, testing of hypotheses, standard errors, t-test, z-test, chi-square test, F-test.
10. Analysis of Variance	One-way classification, Two-way classification
11. Time Series Analysis	Trend determination, Seasonal variation
12. Index Numbers	Construction, Types, Formulae, Uses (e.g., cost of living index)

SSC CGL JSO Paper Overview

Below are the details of SSC JSO Exam:

Feature	Details
Paper Name	SSC CGL Tier 2 Paper II – Statistics (for JSO)
Mode of Exam	Online (Computer-Based Test)
Total Marks	200
No. of Questions	100
Time Duration	2 Hours
Type of Questions	Objective (MCQs)
Negative Marking	0.50 marks per wrong answer

Key Takeaways

Below are the key takeaways:

• SSC CGL JSO Paper tests statistical application and reasoning, not memorization.
• Understanding concepts + practicing numericals = high score.
• Weightage is higher for Probability, Inference, and Correlation.
• Keep a formula sheet handy for last-minute revision.

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