Answer: 0.64

**Explanation:** The standard error of the mean is calculated as: $$SE = \frac{s}{\sqrt{n}}$$ Where: - s = sample standard deviation = 3.5 - n = sample size = 30 $$SE = \frac{3.5}{\sqrt{30}} = \frac{3.5}{5.477} ≈ 0.64$$ Therefore, the standard error of the mean is closest to 0.64.

Author: LeetQuiz Editorial Team