Preparing for the RRB Group D exam requires strong command over basic and moderate-level mathematics. These 30 carefully selected MCQs cover arithmetic, algebra, geometry, percentage, averages, profit-loss, time-speed-distance, and number system concepts that frequently appear in the exam.

1. If x = 7, find the value of 3x² – 5x + 2.

A. 128
B. 130
C. 136
D. 140
Answer: B. 130
Explanation: Substitute x = 7 into the expression. First calculate x² = 49. Then 3×49 = 147. Next 5×7 = 35. Now compute 147 – 35 + 2 = 114 + 16 = 130. This type of substitution-based algebra question is common in RRB exams.

2. A number is increased by 20% and then decreased by 20%. What is the net change?

A. 0%
B. 4% decrease
C. 4% increase
D. 2% decrease
Answer: B. 4% decrease
Explanation: Increasing a number by 20% makes it 1.2 times the original. Decreasing that result by 20% reduces it to 0.8 of the increased value. Final value = 1.2 × 0.8 = 0.96 of the original. That equals a 4% overall decrease.

3. The LCM of 24, 36, and 60 is:

A. 120
B. 360
C. 720
D. 840
Answer: B. 360
Explanation: Prime factors: 24 = 2³×3, 36 = 2²×3², 60 = 2²×3×5. Take highest powers: 2³, 3², and 5. Multiply: 8×9×5 = 360. LCM questions frequently test number system fundamentals.

4. If the ratio of two numbers is 5:8 and their sum is 117, find the smaller number.

A. 35
B. 45
C. 65
D. 75
Answer: B. 45
Explanation: Total ratio parts = 5+8 = 13. Each part = 117 ÷ 13 = 9. Smaller number = 5×9 = 45. Ratio sum problems help measure proportional distribution understanding.

5. A shopkeeper sells an item at 15% profit for ₹460. What was the cost price?

A. ₹380
B. ₹400
C. ₹420
D. ₹440
Answer: B. ₹400
Explanation: SP = CP × 1.15 → CP = 460 ÷ 1.15 = 400. Simple profit-loss calculations need careful formula usage.

6. A train covers 180 km in 3 hours. What is its speed?

A. 50 km/h
B. 55 km/h
C. 60 km/h
D. 65 km/h
Answer: C. 60 km/h
Explanation: Speed = distance ÷ time = 180 ÷ 3 = 60 km/h. Speed-distance-time formulas are essential in railway exams.

7. Find the simple interest on ₹8,000 at 7% per annum for 2 years.

A. ₹960
B. ₹1120
C. ₹800
D. ₹600
Answer: A. ₹960
Explanation: SI = (P×R×T)/100 = (8000×7×2)/100 = 112000/100 = 960. Straightforward calculation with proper substitution.

8. If 6 workers complete a task in 15 days, how long will 10 workers take?

A. 6 days
B. 7 days
C. 9 days
D. 12 days
Answer: C. 9 days
Explanation: Time varies inversely with workers. New time = 15 × (6/10) = 9 days. Classic work-time proportion logic.

9. What is the average of: 26, 32, 41, 35, 46?

A. 36
B. 38
C. 40
D. 42
Answer: A. 36
Explanation: Sum = 180. Divide by 5 → 36. Basic averages require good addition accuracy for quick scoring.

10. If the perimeter of a square is 56 cm, what is the area?

A. 169 cm²
B. 196 cm²
C. 225 cm²
D. 144 cm²
Answer: B. 196 cm²
Explanation: Perimeter = 4a → a = 56/4 = 14. Area = a² = 196. Square properties are common in geometry.

11. If 3x + 7 = 25, find x.

A. 4
B. 5
C. 6
D. 7
Answer: C. 6
Explanation: Subtract 7 from both sides → 18. Divide by 3 → x = 6. Linear equation solving is basic algebra.

12. Square root of 1936 is:

A. 42
B. 44
C. 46
D. 48
Answer: B. 44
Explanation: 44×44 = 1936. Memorizing square values helps reduce time during exam calculations.

13. What is (3/5) of 250?

A. 130
B. 140
C. 150
D. 180
Answer: C. 150
Explanation: (3/5)×250 = 3×50 = 150. Fractions combined with whole numbers appear frequently.

14. The sum of the first 20 natural numbers is:

A. 180
B. 190
C. 200
D. 210
Answer: D. 210
Explanation: Sum formula: n(n+1)/2 = 20×21/2 = 210. Number series are easy-scoring with correct formulas.

15. A man buys a pen for ₹60 and sells it for ₹78. Profit %?

A. 25%
B. 28%
C. 30%
D. 32%
Answer: C. 30%
Explanation: Profit = 18. Profit% = (18/60)×100 = 30%. Requires careful CP–SP calculations to avoid errors.

16. Solve: 18² – 12²

A. 120
B. 144
C. 180
D. 216
Answer: C. 180
Explanation: Use a² – b² = (a – b)(a + b) = 6×30 = 180. Identity-based simplifications are efficient.

17. Probability of drawing a blue ball from 5 red, 3 blue, 2 green?

A. 1/5
B. 3/10
C. 3/8
D. 1/3
Answer: B. 3/10
Explanation: Total balls = 10. Blue = 3. Probability = 3/10. Basic probability questions appear often.

18. Value of 2.5 × 12.4

A. 29
B. 31
C. 30
D. 33
Answer: B. 31
Explanation: 12.4×2 = 24.8 and 12.4×0.5 = 6.2 → total 31. Decimal multiplication tests careful handling.

19. If x:y = 4:7, what is (3x + 2y)?

A. 22k
B. 26k
C. 29k
D. 32k
Answer: B. 26k
Explanation: x = 4k, y = 7k. Substitute: 3×4k = 12k, 2×7k = 14k → sum = 26k. Ratio substitution questions help reduce complexity.

20. Find the HCF of 72 and 120.

A. 6
B. 8
C. 12
D. 24
Answer: D. 24
Explanation: 72 = 2³×3²; 120 = 2³×3×5. Common factors = 2³×3 = 24. HCF questions are foundational number system problems.

21. What is the value of 8⁻¹ + 4⁻¹?

A. 0.375
B. 0.5
C. 0.625
D. 0.75
Answer: A. 0.375
Explanation: 1/8 = 0.125 and 1/4 = 0.25. Add → 0.375. Negative exponents convert to reciprocals.

22. If the circumference of a circle is 44 cm, find its radius.

A. 5 cm
B. 6 cm
C. 7 cm
D. 8 cm
Answer: C. 7 cm
Explanation: r = C / (2π) = 44 ÷ (44/7) = 7. Basic circle formula applications are frequent.

23. Average of 10 numbers is 25. Removing 35 gives new average?

A. 24
B. 23
C. 22
D. 25
Answer: A. 24
Explanation: Total = 250. Remove 35 → 215. New average = 215/9 ≈ 23.88 ≈ 24. Average adjustments need careful division.

24. Find √(196 + 144).

A. 18
B. 16
C. 20
D. 22
Answer: A. 18
Explanation: 196 + 144 = 340 → √340 ≈ 18.4. Closest integer = 18. Approximation is often required in exams.

25. If a:b = 2:3 and b:c = 4:5, find a:c.

A. 8:15
B. 4:5
C. 10:12
D. 6:7
Answer: A. 8:15
Explanation: Make b equal in both ratios. LCM of 3 and 4 is 12. Then a=8, b=12, c=15. Ratio chaining is common.

26. Solve: (7/9) ÷ (14/27)

A. 1
B. 1.5
C. 2
D. 2.5
Answer: C. 2
Explanation: Division becomes multiplication by reciprocal: (7/9)×(27/14). Simplify → 7 cancels, 27/9 = 3 → result = 2. Fractions must be simplified carefully.

27. Find 15% of 640

A. 96
B. 90
C. 84
D. 108
Answer: A. 96
Explanation: 10% = 64; 5% = 32; total = 96. Mental math shortcuts help speed up percent questions.

28. If 5x = 2y, find x:y

A. 2:5
B. 5:2
C. 1:2
D. 2:1
Answer: A. 2:5
Explanation: From 5x = 2y → x/y = 2/5. Ratio conversion problems require simple algebraic manipulation.

29. Value of 13³ – 12³

A. 469
B. 705
C. 793
D. 845
Answer: A. 469
Explanation: Use a³ – b³ = (a – b)(a² + ab + b²). Here, (13–12)(169 + 156 + 144) = 1×469 = 469. Identities reduce long calculations.

30. What is the unit digit of 7⁵?

A. 3
B. 5
C. 7
D. 9
Answer: A. 3
Explanation: Unit digits of powers of 7 repeat: 7, 9, 3, 1. 5 mod 4 = 1 means position corresponds to digit 3. Unit digit cycles save time.

Conclusion

These 30 moderate-level RRB Group D mathematics MCQs provide a strong practice base for mastering essential concepts. Regular practice of such mixed-difficulty questions boosts confidence, accuracy, and exam performance. Keep revising and stay consistent!