A cartwheel of diameter 1.4 m makes 500 complete revolutions along a straight track. What distance does the cart travel, in metres? (Use π = 22/7.)

One revolution carries the cart forward by the wheel's circumference, π$d=(22/7)\times 1.4=4.4$ m, so 500 revolutions cover $4.4\times 500=2200$ m. The trap 1100 uses π$r=2.2$ m, taking the given 1.4 m as the radius; 4400 uses 2π$d$, doubling a circumference that already used the diameter; 770 uses the wheel's AREA π$r^2=1.54$ sq m as if it were the distance per turn.