RRB Aptitude MCQs – Ratio & Proportion - 02 Feb 2026
1. The ratio of boys to girls in a class is 7 : 5.
If the total number of students is 48,
how many girls are there in the class?
2. The ratio of the ages of A and B is 4 : 5.
After 6 years, the ratio becomes 5 : 6.
What is the present age of A?
- A) 20 years
- B) 24 years
- C) 28 years
- D) 32 years
3. If the ratio of milk to water in a mixture is 3 : 2,
how much water should be added to 20 litres of the mixture
to make the ratio 3 : 4?
- A) 6 litres
- B) 8 litres
- C) 10 litres
- D) 12 litres
4. Two numbers are in the ratio 5 : 7.
If their difference is 24,
what is the smaller number?
5. The salaries of A and B are in the ratio 6 : 5.
If A’s salary is ₹18,000,
what is B’s salary?
- A) ₹12,000
- B) ₹14,000
- C) ₹15,000
- D) ₹16,000
Explanation
Q1: Total ratio = 7 + 5 = 12 → Each part = 48 ÷ 12 = 4 → Girls = 5 × 4 = 20.
Q2: Let ages be 4x and 5x → (4x + 6)/(5x + 6) = 5/6 → x = 6 → A = 4 × 6 = 24 years.
Q3: Milk = 12 L, Water = 8 L → To make 3 : 4, water must be 16 L → Added water = 8 L.
Q4: Difference = 7x − 5x = 2x = 24 → x = 12 → Smaller number = 5 × 12 = 60.
Q5: One part = 18,000 ÷ 6 = 3,000 → B = 5 × 3,000 = ₹15,000.
Expert Tip: Ratio & Proportion (RRB)
Ratio & Proportion questions are highly scoring in RRB exams.
Always find the value of one part first.
For age-based ratios, form a simple equation instead of guessing.
This topic is frequently combined with age, mixture, and salary problems,
making it important for RRB NTPC and Group-D preparation.