Table 4. Results of Statistical Processing of Measurements of Ca Content in Graphite by Variants A, B, C, and D.

calculation option	average Ca content, %	Δ1	Ka, %, n = 15, p = 0.95
(A) formula 4, Tables 1 and 2	0.072	0.005	3.8
(B) formula 2, Tables 1 and 2	0.075	0.004	2.9
(C) formula 4, Tables 1 and 3	0.075	0.006	4.4
(D) formula 2, Tables 1 and 3	0.113	0.043	21

^a, t(n, p) is Student’s coefficient, t(15, 0.95) = 2.131.