To predict how many minutes Felipe would need to memorize a 17-letter word using the least squares regression line \( y = 3.477x - 50.707 \), we simply need to plug in \( x = 17 \) into the equation.
\[ y = 3.477(17) - 50.707 \]
Calculating \( 3.477 \times 17 \):
\[ 3.477 \times 17 = 59.109 \]
Now we will subtract \( 50.707 \):
\[ y = 59.109 - 50.707 = 8.402 \]
Thus, the predicted time for Felipe to memorize a 17-letter word is:
\[ \boxed{8.402} \text{ minutes} \]