The mean distance of mars from the sun is 1.524 times that of the earth from the sun. Find the
number of years required for mars to make one revolution about the sun.

For planets revolving around the sun ${\mathrm{T}}^2\alpha {\mathrm{r}}^3$

$\Rightarrow \frac{{\mathrm{T}}_1^2}{{\mathrm{T}}_2^2}=\frac{{\mathrm{r}}_1^3}{{\mathrm{r}}_3^2}({\mathrm{T}}_1=\text{time period of mass,}$

${\mathrm{T}}_2=\text{time period of the earth)}$

$\frac{{\mathrm{T}}_1}{{\mathrm{T}}_2}={\left(\frac{{\mathrm{r}}_1}{{\mathrm{r}}_2}\right)}^{3/2}$

$\Rightarrow {\mathrm{T}}_1={\mathrm{T}}_2{\left(\frac{{\mathrm{r}}_1}{{\mathrm{r}}_2}\right)}^{3/2}=\left(1\text{year}\right)(1.524{)}^{3/2}$

= 1.88 years