To solve the inequality \( \sqrt{2n} < 5 \), we'll first square both sides to eliminate the square root:
\[ 2n < 25 \]
Now, divide both sides by 2:
\[ n < 12.5 \]
So, the values of \( n \) that satisfy the inequality must be less than 12.5. Now let's evaluate the options:
- 16: \( 16 \) is not less than \( 12.5 \).
- 8: \( 8 \) is less than \( 12.5 \) (valid).
- 18: \( 18 \) is not less than \( 12.5 \).
- 12.5: \( 12.5 \) is not less than \( 12.5 \).
Therefore, the only value for \( n \) that satisfies the inequality \( \sqrt{2n} < 5 \) is 8.