To solve the inequality \( \sqrt{2n} < 5 \), we can first square both sides to eliminate the square root (as long as we know both sides are non-negative):
\[ 2n < 25 \]
Next, we divide both sides by 2 to isolate \( n \):
\[ n < 12.5 \]
Now we can evaluate the options given:
- 8: \( 8 < 12.5 \) (True)
- 16: \( 16 < 12.5 \) (False)
- 18: \( 18 < 12.5 \) (False)
- 12.5: \( 12.5 < 12.5 \) (False)
The only value for \( n \) that makes the inequality true is:
8.