Using graphite furnace atomic absorption spectrometry, the mean cadmium (Cd2 ) c

Question

Using graphite furnace atomic absorption spectrometry, the mean cadmium (Cd2 ) content value in a homogenized sample of 40 zebra mussles was found to be 6.40 ppb Cd2 with a standard deviation (s) of 0.63 ppb Cd2 (assume that s is a good approximation of ). Calculate the 90% and 95% confidence intervals (CI) for: (A) two analyses and (B) five analyses of this homogenized sample.

Question 29 of 37 Map Sapling Learning Using graphite furnace atomic absorption spectrometry. the mean cadmium (Cd content value in a homogenized sample of 40 zebra mussles was found to be 6.40 ppb cd with a standard deviation (s) of 0.63 ppb cd2 (assume that sis a good approximation of Calculate the 90% and 95% confidence intervals (CI) for: (A) two analyses and (8) five analyses of this homogenized sample. Number Number (A) 90% CI 6.40 t 95% CI 6.40 0 ppb ppb Number (B) 90% CI 6.40 t O ppb 95% CI 6.40 0 ppb AS Previous Give up view solution Check Answer ONext Exit Hint

Explanation / Answer

95 % critical value=2.0227

90% critical value=1.6849

95% confidence interval of critical value=2.0227*0.63/sqrt(40)=0.2015

two analyses=0.2015*2=0.403

five analyses=0.2015*5=1.0075

90% confidence interval of critical value =1.6849*0.63/sqrt(40)=0.1678

two analyses=0.1678*2=0.3356

five analyses=0.1678*5=0.839

90% confidence interval

Two analyses=6.40+-0.3356=6.0644 to 6.7356

Five analyses=6.40+-0.839=5.561 to 7.239

95% confidence interval

Two analyses=6.40+-0.403=5.997 to 6.803

Five analyses=6.40+-1.0075=5.3925 to 7.4075

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