EXPLANATION
Since he only made 13 from 19 throws, the percent error is as shown as follows:
[tex]Percent\text{ error=}\frac{\parallel measured-real\parallel}{real}*100[/tex]Plugging in the numbers into the expression:
[tex]Percent\text{ error=}\frac{\parallel19-13\parallel}{13}*100[/tex]Subtracting numbers:
[tex]Percent\text{ error=}\frac{6}{13}*100[/tex]Multiplying terms:
[tex]Percent\text{ error=46.15\%}[/tex]In conclusion, the percent error was 46.15%