Mensuration — RRB NTPC Study Notes

Overview

Mensuration is the quantitative study of geometric figures — computing area, perimeter, surface area and volume. For RRB NTPC, this topic consistently delivers 2–4 direct questions each year, making it a high-yield area. Questions test both formula recall and the ability to apply formulas to word problems involving real-world objects like water tanks, metal sheets, ground plots, and packaging.

Mastery means knowing the right formula instantly and executing arithmetic cleanly. Most errors come from unit confusion (mixing cm and m), incorrect formula selection (lateral vs. total surface area), or algebraic slips when solving for an unknown dimension. Since mensuration questions are computation-heavy, speed and accuracy in multiplication, squaring, and handling π are critical.

The syllabus explicitly covers 2-D shapes (triangle, rectangle, square, circle, trapezium) and 3-D solids (cube, cuboid, cylinder, cone, sphere, hemisphere). You won't see complex composite solids, but do expect problems combining two shapes or converting between volume and capacity (1 litre = 1000 cm³).

Key Concepts

• **Area** measures the space inside a 2-D boundary; units are always square (cm², m², etc.). Perimeter measures the boundary length itself.