Step 1 :The standard deviation is the square root of the variance. So, to find the standard deviation, we need to take the square root of the sample variance. In this case, the sample variance is 39.1.
Step 2 :Calculate the square root of the variance: \( \sqrt{39.1} = 6.252999280345393 \)
Step 3 :Round the result to one decimal place: \( 6.3 \)
Step 4 :Final Answer: The best point estimate for the population's standard deviation is \( \boxed{6.3} \)