Question

How to solve this problem

Answer 1

$\bf \textit{circumference of a circle}\\\\ C=2\pi r\quad \begin{cases} r=radius\\ -----\\ r=10 \end{cases}\implies C=2\pi 10\implies \boxed{C=20\pi }\\\\ -------------------------------$

$\bf \textit{let's converte 1km to inches} \\\\\\ km\cdot \cfrac{1000m}{km}\cdot \cfrac{100cm}{m}\cdot \cfrac{in}{2.54cm}\implies \cfrac{1000\cdot 100\cdot in}{2.54}\approx 39370.079\ in\\\\ -------------------------------\\\\ \textit{how many times does }20\pi \textit{ go into }39370.079?\implies \boxed{\cfrac{39370.079}{20\pi }}$