NORTHERN CARIBBEAN UNIVERSITY
College of Natural and Applied Sciences, Allied Health and Nursing
Department of Biology, Chemistry and Environmental Science
BCHM390: Analytical Biochemistry
Spring 2023
Instructions: Given the following measurements of protein concentration in a urine sample :
4.2, 3.8, 3.9, 4.4, 4.0 g/dL calculate the mean, Standard Deviation and Standard Error. Also
provide the range that corresponds to the probability of finding the mean at 95% confidence.
µ (population mean) = x̄(mean) ± ts/√n
Given t for 4 degrees of Freedom and 95% confidence = 2.776
Mean =
𝑥̅ =
SD = √
SD=√
4.2 + 3.8 + 3.9 + 4.4 + 4.0
=
5
4.06 ≈ 4.1 g/dL
∑(𝑥−𝑥̅ )2
𝑛−1
(4.2−4.1)2 +(3.8−4.1)2 +(3.9−4.1)2 +(4.4−4.1)2 +(4.0−4.1)2
5−1
SD= 0.244 ≈ 0.24 g/dL
SE =
𝑠
√
=
𝑛
Range using
0.24
√5
= 0.1073 ≈ 0.11 g/dL
µ = x̄ ± t
4.1 ± (2.776 × 0.11)
𝑠
√𝑛
= 4.1 ± 0.31 g/dL
(3.79, 4.41) ≈ (3.8, 4.4)
Range of finding mean at 95% confidence (3.8, 4.4)