Calculate the mean and standard deviation for the results below for the concentration of lead in a soil sample. 23.2 ppm,20.1 ppm,24.7 ppm,19.9 ppm,21.8 ppm
A)21.9 $\pm$ 3.4 (n = 5)ppm
B)21.9 $\pm$ 2.0 (n =5)ppm
C)27.4 $\pm$2.0 (n = 5)ppm
D)22.0 $\pm$ 1.8 (n = 5)ppm
E)27.4 $\pm$ 4.2 (n = 5)ppm

Question

Quizplus · Accepted Answer

First, calculate the mean: (23.2 + 20.1 + 24.7 + 19.9 + 21.8) / 5 = 109.7 / 5 = 21.94 ppm, which rounds to 21.9 ppm. Then, calculate the standard deviation: sqrt(((23.2-21.94)^2 + (20.1-21.94)^2 + (24.7-21.94)^2 + (19.9-21.94)^2 + (21.8-21.94)^2) / (5-1)) = sqrt((1.5876 + 3.3856 + 7.6324 + 4.1616 + 0.0196) / 4) = sqrt(16.7868 / 4) = sqrt(4.1967) ≈ 2.048, which rounds to 2.0 ppm.

Calculate the Mean and Standard Deviation for the Results Below ±\pm±

Calculate the Mean and Standard Deviation for the Results Below $\pm$