Question

A certain star is 1.7 x 102 light years from the Earth. One light year is about 5.9 x 1012 miles. How far from the earth (in miles) is the star?

Answer 1

The star is 1.7 * 10^2 light years from the earth. Given that one light year is about 5.9 * 10^12 miles, then the distance of the star from the earth is

$\begin{gathered} 1.7\text{ }\times10^2\times5.9\times10^{12} \\ =\text{ }10.03\text{ }\times10^{2+12} \\ =10.03\times10^{14} \\ =\text{ 1.003 }\times10^{15}\text{ miles} \end{gathered}$