# Analytical Chemistry: Analyses of samples of Hg in fish give the following data for three trials: ppm Hg = 1.80, 1.58, 1.64 a) Calculate the 95% CI for the mean when s is a good estimation of σ...

Analytical Chemistry:

Analyses of samples of Hg in fish give the following data for three trials:

# ppm Hg = 1.80, 1.58, 1.64

Answer: 1.67 (+/- 0.11) ppm.

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`Mean = bar x = (sum (x))/n`

n = number of values/population = 3

`bar x = (1.80 + 1.58 + 1.64)/(3) `

`bar x = 1.67 `

Standard deviation = `s = sqrt((sum (x-bar x))/(n-1))`

`s =sqrt((sum (x-bar x)^2)/(n-1)) `

`s = sqrt(((1.80-1.67)^2 + (1.58-1.67)^2 + (1.64-1.67)^2)/2) `

`s = 0.11 `

*If s is a good estimation of sigma

**Answer = 1.67 (+/1 0.11) ppm**

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