To find out what percent of the free throws the basketball player missed, we start by determining how many he missed.
He made 5 out of 6 free throws, which means:
\[ \text{Free throws missed} = 6 - 5 = 1 \]
Next, we need to find the percentage of missed free throws relative to the total number of attempts. The formula to calculate the percentage of missed free throws is:
\[ \text{Percentage missed} = \left( \frac{\text{Free throws missed}}{\text{Total attempts}} \right) \times 100 \]
Substituting in the values:
\[ \text{Percentage missed} = \left( \frac{1}{6} \right) \times 100 \approx 16.67% \]
So, rounding gives us approximately \( 16.67% \), which can be expressed as \( 16.66\overline{6}% \).
Therefore, the correct answer is:
16.66¯¯¯¯¯ %