IBPS RRB Formula Sheet
Ten formulas, what each one is for, and a worked example.
IBPS RRB sets maths for both Officer Scale I and Office Assistant, with a strong rural and agricultural flavour in its word problems. Mixtures, mensuration and quadratic comparisons turn up often.
These ten formulas cover the paper, with a worked mixtures example.
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The 10 Formulas
1
Formula
Percentage change
Expression
(New − Old) ÷ Old × 100
Use it for
Growth and fall in values, and the base of most DI questions.
2
Formula
Profit %
Expression
(SP − CP) ÷ CP × 100
Use it for
Profit or loss on cost price.
3
Formula
Simple interest
Expression
SI = P × R × T ÷ 100
Use it for
Interest that isn't added back to the principal.
4
Formula
Compound interest
Expression
A = P × (1 + R/100)ᵀ; CI = A − P
Use it for
Interest compounded once a year.
5
Formula
Alligation (mixtures)
Expression
Cheaper : Dearer = (Dearer − Mean) : (Mean − Cheaper)
Use it for
Ratio in which two items are mixed to reach a mean price.
6
Formula
Circle
Expression
Area = πr²; Circumference = 2πr
Use it for
Mensuration questions on wheels, tracks and plots.
7
Formula
Cylinder volume
Expression
V = πr²h; Curved surface = 2πrh
Use it for
Tanks, pipes and containers.
8
Formula
Quadratic roots
Expression
x = [−b ± √(b² − 4ac)] ÷ 2a
Use it for
Quadratic-equation comparison questions (x vs y).
9
Formula
Speed, distance, time
Expression
Distance = Speed × Time; km/h × 5/18 = m/s
Use it for
Trains, journeys and unit conversions.
10
Formula
Average
Expression
Sum of observations ÷ Number of observations
Use it for
Averages, and finding a missing or replaced value.
| # | Formula | Expression | Use it for |
|---|---|---|---|
| 1 | Percentage change | (New − Old) ÷ Old × 100 | Growth and fall in values, and the base of most DI questions. |
| 2 | Profit % | (SP − CP) ÷ CP × 100 | Profit or loss on cost price. |
| 3 | Simple interest | SI = P × R × T ÷ 100 | Interest that isn't added back to the principal. |
| 4 | Compound interest | A = P × (1 + R/100)ᵀ; CI = A − P | Interest compounded once a year. |
| 5 | Alligation (mixtures) | Cheaper : Dearer = (Dearer − Mean) : (Mean − Cheaper) | Ratio in which two items are mixed to reach a mean price. |
| 6 | Circle | Area = πr²; Circumference = 2πr | Mensuration questions on wheels, tracks and plots. |
| 7 | Cylinder volume | V = πr²h; Curved surface = 2πrh | Tanks, pipes and containers. |
| 8 | Quadratic roots | x = [−b ± √(b² − 4ac)] ÷ 2a | Quadratic-equation comparison questions (x vs y). |
| 9 | Speed, distance, time | Distance = Speed × Time; km/h × 5/18 = m/s | Trains, journeys and unit conversions. |
| 10 | Average | Sum of observations ÷ Number of observations | Averages, and finding a missing or replaced value. |
Worked Example: Mixing Two Grades
Rice at ₹30/kg is mixed with rice at ₹45/kg to sell the mix at ₹40/kg with no profit or loss. In what ratio are they mixed?
- 1
Dearer − Mean
45 − 40 = 5.
- 2
Mean − Cheaper
40 − 30 = 10.
- 3
Ratio
Cheaper : Dearer = 5 : 10 = 1 : 2.
Questions from this exact syllabus. No signup.
Keep Units Consistent in Mensuration
Mensuration questions often mix metres and centimetres, or ask for litres from cubic centimetres (1,000 cm³ = 1 litre). Convert first, calculate second.
FAQs
Is the maths the same for Officer Scale I and Office Assistant?expand_more
The topics are similar. Officer Scale I questions are usually a little harder.
Are quadratic equations asked in IBPS RRB?expand_more
Yes, commonly as x vs y comparisons in Prelims.
Is the value of π given?expand_more
Use 22/7 unless the question says otherwise.
Next steps
Take a full IBPS RRB mock testThe whole syllabus, timed and scored like the real paper.