Question

In an investigation of toxins produced by molds that infect corn crops, a biochemist prepares extracts of the mold culture with organic solvents and then measures the amount of the toxic substance per gram of solution. From 14 preparations of the mold culture, the following 98% confidence interval for the average amount of the toxic substance per gram of solution was produced, (1.29, 1.71). What was the sample standard deviation?

Answer 1

Solution :

Sample mean = = (1.29 + 1.71) / 2 = 1.5

Margin of error = E = Upper confidence interval -   = 0.21

df = 13

t_/2,df = 2.650

s = E * n / t_/2,df

= 0.21 * 16 / 2.650

= 0.317

sample standard deviation = 0.317 = 0.32