The diameters of the front and rear wheels of a tractor are 80 cm and 2 m respectively. Find the number of revolutions that rear wheel will make to cover the distance which the front wheel covers in 1400 revolutions.
Let us find the distance covered by front wheel in 1400 revolutions.
We know that distance covered in n revolutions is equal to multiplication of number of revolutions and circumference of wheel.
$\therefore$ distance $=n \times 2 \times \pi \times r$
We have $r=80 \mathrm{~cm}$ therefore, we will convert it meters.
$\therefore r=0.8 \mathrm{~m}$
Now we substitute the values.
$\therefore$ distance $=1400 \times 2 \times \frac{22}{7} \times 0.8$
$\therefore$ distance $=7040$
Now we will calculate the number of revolutions that rear wheel will make to cover 7040 m.
$\therefore$ revolutions $=\frac{\text { Distance }}{\text { Circumference }}$
$\therefore$ revolutions $=\frac{7040}{2 \times \frac{22}{7} \times 2}$
$\therefore$ revolutions $=\frac{7040 \times 7}{88}$
$\therefore$ revolutions $=\frac{49280}{88}$
$\therefore$ revolutions $=560$
Therefore, the rear wheel will make 560 revolutions to cover $7040 \mathrm{~m}$.