An analyst is assigned a blind quality control sample of blood containing a drug metabolite. He tests ten separate portions and obtains the following data for the concentration in ug/mL:
25.2
24.8
26.6
27.0
24.0
26.0
25.5
26.3
24.9
23.9
Calculate the mean value and report to three significant figures. Use a spreadsheet or calculator

Question

Quizplus · Accepted Answer

To calculate the mean value, we need to add up all the measurements and divide by the number of measurements taken. 
25.2 + 24.8 + 26.6 + 27.0 + 24.0 + 26.0 + 25.5 + 26.3 + 24.9 + 23.9 = 254
We have 10 measurements, so we divide 254 by 10:
254 / 10 = 25.4
Therefore, the mean value is 25.4 ug/mL, rounded to three significant figures. The best choice is D.

An Analyst Is Assigned a Blind Quality Control Sample of Blood