Question

The diameter of a wheel is $40cm$. How many revolutions will it make in covering $176m$?
(a) $140$
(b) $150$
(c) $160$
(d) $166$

Answer 1

Distance covered by the wheel in $1$ revolution$=2\pi r$
$=\pi d$ [since $2r=d$]
$=\frac{22}{7}\times 40cm$
$=\frac{880}{7}cm=\frac{880}{7\times 100}m$
Number of revolutions required to cover $176m$
$=\frac{176}{\left(\frac{880}{7\times 100}\right)}$
$=\frac{176\times 100\times 7}{880}$
$=2\times 10\times 7$
$=140$
Hence, the number of revolutions is $140$ Therefore, the correct option is (a) $\left(140\right)$