Answer: 0.64

## Explanation The standard error of the mean (SEM) is calculated using the formula: $$SEM = \frac{s}{\sqrt{n}}$$ Where: - $s$ = sample standard deviation = 3.5 - $n$ = sample size = 30 Substituting the values: $$SEM = \frac{3.5}{\sqrt{30}} = \frac{3.5}{5.477} ≈ 0.639$$ This value (0.639) is closest to **0.64** among the given options. **Key points:** - Standard error measures the precision of the sample mean as an estimate of the population mean - It decreases as sample size increases - The formula assumes the sample is representative of the population - In this case, with n=30, we get SEM ≈ 0.64

Author: LeetQuiz .