The Concentration (In % by Volume) of Methyl Tert-Butyl Ether

The concentration (in % by volume) of methyl tert-butyl ether (MTBE) was determined in four samples of the same gasoline. What is the average value, and which measurement was the most accurate, compared to the average? Sample % (v/v) MTBE
1 5.01
2 4.95
3 5.10
4 5.15

A) 5.05, sample 1
B) 5.05, sample 2
C) 5.05, sample 3
D) 5.05, sample 4
E) 5.0525, sample 3