A garden roller is a cylinder 1.4 $m$ long whose diameter is 0.7 $m$. Find the area of ground it levels in one complete revolution, in $m^2$. Take π = 22/7.

In one revolution the roller lays down its curved surface, a rectangle whose width is the roller's length and whose length is the circumference. Circumference = π$d=(22/7)\times 0.7=2.2$ m, so the area = $2.2\times 1.4=3.08{\text{m}}^2$. (Using the radius in place of the diameter would wrongly give $1.54{\text{m}}^2.$)