Practice30 Create account

The drum of a road roller is 1.5 m long, with the diameter shown. How much road area does it level in 200 full revolutions? (Take π = 22/7.)

Class 8MensurationMensuration

A $660 m^{2}$
B $1320 m^{2}$
C $3.3 m^{2}$
D $330 m^{2}$

Step-by-Step Solution

One revolution covers the curved surface

= 2 π r h = 2 \times \frac{22}{7} \times 0.35 \times 1.5 = 3.3 m^{2}

. In 200 revolutions:

3.3 \times 200 = 660 m^{2}

.

Answer: A)

660 m^{2}

Key idea: Surface area and volume of a cylinder

A cylinder is a circle stacked vertically. Two measurements: radius

r

and height

h

.

**Curved surface area (CSA) = 2π

r h

** (imagine 'unrolling' the curved surface — it becomes a rectangle of width 2π

r

and height h).

**Total surface area (TSA) = 2π

r^{2} + 2

π

r h = 2

π

r (r + h)

** (curved surface + two circular ends).

**Volume = π

r^{2}

h

** (area of circular base × height).

Use π = 22/7 when

r

is a multiple of 7; otherwise π ≈ 3.14.

Master this chapter in 30 minutes a day.

Don't just memorise the answer — build a daily practice habit.

Practice 5 Similar Questions Free →

All Mensuration practice questions

More Class 8 Mensuration practice

A cylindrical milk can has the radius and height shown. The milk in the full can is…Which of the following is the correct VOLUME formula for a cylinder of radius r and…A quadrilateral with at least one pair of parallel sides is called a ______.Surface area is measured in which type of units?Find the TSA of a cuboid 8 cm × 6 cm × 5 cm.