The point estimate of the population standard deviation as per the below mentioned data from a simple random sample 6, 10, 15, 12, 9, 8 will be:-
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 3.162
Given data: 6, 10, 15, 12, 9, 8
Number of observations: $n = 6$
Sample mean:
$\bar{x} = \frac{6+10+15+12+9+8}{6} = \frac{60}{6} = 10$
Deviations squared:
$(6-10)^2 = 16$
$(10-10)^2 = 0$
$(15-10)^2 = 25$
$(12-10)^2 = 4$
$(9-10)^2 = 1$
$(8-10)^2 = 4$
Sum of squared deviations $= 16+0+25+4+1+4 = 50$
Sample variance (unbiased estimator):
$s^2 = \frac{\sum (x_i-\bar{x})^2}{n-1} = \frac{50}{6-1} = \frac{50}{5} = 10$
Sample standard deviation (point estimate of population standard deviation):
$s = \sqrt{10} \approx 3.162$