Q:

The distances in space are measured in light-years. The distance from Earth to a star is 5.9 × 1013 kilometers. What is the distance, in light-years, from Earth to the star (1 light-year = 9.46 × 1012 kilometers)?

Accepted Solution

A:
The answer is:  "6.2 light years" .
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{ Note:  There are no answer choices provided.  If there are supposed to be, then round to answer choice closest to  " 6.2 light years ". }.
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Explanation:
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   [tex](5.9 * 10^1^3 km) * ( \frac{1 light year}{9.46 *10^1^2 km} [/tex]  ;

=  ([tex] \frac{5.9 * 10^1^3 km}{9.46 * 10^1^2 km} [/tex]  light years ;  

=   [tex] \frac{5.9 km}{9.46 km} * (10^1^3^-^1^2)[/tex]  light years ;

=   [tex] \frac{5.9 km}{9.46 km} * (10^1)[/tex]  light years ;

=   [tex] \frac{5.9 km}{9.46 km} * (10)[/tex]  light years ;

=   [tex] \frac{5.9 km}{9.46 km} * (10)[/tex]  light years ;

=   [tex] \frac{5.9 km * 10}{9.46 km}[/tex]   light years ;

=   [tex] \frac{59 km}{9.46 km}[/tex]  light years ;

Note:  We can "cancel out" BOTH of the units of  "km" ; 

        →  {since:  "km/km = 1 "} ;  and rewrite:
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=   [tex] \frac{59}{9.46}[/tex]  light years ;

=   " { 59 ÷ 9.46 } "  light years ; 

=     6.2367864693446089 light years.
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Round to "6.2 light years" ; since there are no answer choices provided.
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