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Student A Student B Measurement #1. 3.20 g/mL 2.82 g/mL Measurement #2. 2.58 g/m

ID: 819797 • Letter: S

Question

                                               Student A          Student B


Measurement #1.               3.20 g/mL          2.82 g/mL

Measurement #2.               2.58 g/mL          2.48 g/mL

Measurement #3.               2.10 g/mL          2.59 g/mL

mean:                                   2.63 g/mL           2.63 g/mL


Correct density: 2.65 g/mL


I know that student B is more precise, but I am not sure which is more accurate because both average the same density. Is it the average that matters for accuracy? or each individual measurement?

Explanation / Answer

var(a) = (3.2-2.63)^2 + (2.58-2.63)^2 + (2.10-2.63)^2

var(b) = (3.2-3.82)^2 +(3.2-3.48)^2 +(3.2-3.59)^2

Student B is more accurate because his variance of readings is less