c and d please

accepted value - 60% & average value - 67% & most frequent value - 68%

Range of values - 9

Standard deviation - 2.8

Data

%Mg	Frequency
60	0
61	1
63	2
65	2
67	2
68	4
69	1
70	3

c. Is there evidence for either random or systematic error? How do you know? d. If there is evidence of systematic error, what do you suggest is the cause