SSC CGL 2024 Tier-I · 13 September 2024, Shift 3 · Quantitative Aptitude · Question 2 of 98

Text as printed on a candidate's response sheet for this shift; answer per SSC's tentative key as marked on that sheet. Solution last reviewed 6 September 2026.

Where this paper and its answers come from

SSC does not publish CGL question papers or a public answer key. The questions and options here are reproduced as printed on a candidate's own response sheet for this shift — the Commission's text, unchanged. Each answer is SSC's tentative key as marked on that sheet; SSC allowed challenges to it and never publishes a final key. The solutions are written by UnlockIAS.

If the curved surface area of a cylinder is 880 cm 2 , then the product of its height and radius is:

(a)120 cm
(b)140 cm
(c)90 cm
(d)220 cm

Answer

Why

Correct — B. Curved surface area of a cylinder = 2πrh — the lateral wall only, with no circular ends. The question wants the product rh, so r and h never need separating.

2πrh = 880
rh = 880 ⁄ (2π)

With π = 22⁄7:
rh = (880 × 7) ⁄ (2 × 22)
rh = 6160 ⁄ 44 = 140 → option (b)

Why the others are wrong

(a)
120 cm — 120 would make the curved surface 2 × (22⁄7) × 120 ≈ 754 cm², well under the 880 cm² the question states.
(c)
90 cm — 90 gives a curved surface of 2 × (22⁄7) × 90 ≈ 566 cm². That is barely two thirds of 880, so the product is far too small.
(d)
220 cm — 220 is 880 ÷ 4 — the value you reach by dividing by 2π as though π were 2. The true divisor 2π ≈ 6.28 gives 140.

Concept

A cylinder carries three formulas that are easy to confuse. Curved surface area is 2πrh, the rectangle you get by unrolling the side wall — its length is the base circumference 2πr and its height is h.

Total surface area adds the two circular ends: 2πrh + 2πr² = 2πr(r + h). Volume is a different quantity again, πr²h.

Because 2πrh depends on r and h only as a product, one equation is enough to pin rh even though r and h stay unknown.

The options are labelled 'cm', but a product of two lengths is an area. The paper's unit is loose here; read the keyed answer as 140 cm². The number, not the unit, is what the key marks.

Key facts

Curved (lateral) surface area of a right circular cylinder = 2πrh.
Total surface area of a cylinder = 2πr(r + h), which adds the two circular ends.
Volume of a cylinder = πr²h.
2 × (22⁄7) × 140 = 880 exactly, which is why 22⁄7 and not 3.14 is the intended value here.

Study next

Total surface area of a cylinder, and spotting when a question wants the ends includedCurved surface area of a cone, πrl, and of a sphere, 4πr²Cylinder problems posed entirely in ratios of r and h

Common traps

Using the total surface area 2πr(r + h) when the question says curved surface area.
Taking π = 3.14, which leaves rh ≈ 140.1 and invites needless rounding doubt.
Hunting for r and h separately when only their product is asked for.

SSC also hands this formula as a ratio rather than a number, which removes π entirely from the working.

Ratio of curved surface areas from r and h ratios is asked at 12 Sep 2024, 12:30, Quant Q.19, and the ratio of total surface area to curved surface area at 17 Sep 2024, 12:30, Quant Q.9.

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