Observation	Diameter(Cm)(X)	(X-Xbar)	(X-Xbar)2
1	91.89	-2.47	6.10
2	92.66	-1.7	2.89
3	99.45	5.09	25.91
4	97.81	3.45	11.90
5	91.83	-2.53	6.40
6	93.6	-0.76	0.58
7	94.77	0.41	0.17
8	97.69	3.33	11.09
9	91.77	-2.59	6.71
10	98.68	4.32	18.66
11	93.23	-1.13	1.28
12	94.45	0.09	0.01
13	92.43	-1.93	3.72
14	96.73	2.37	5.62
15	94.17	-0.19	0.04
16	94.76	0.4	0.16
17	90.26	-4.1	16.81
18	92.71	-1.65	2.72
19	93.84	-0.52	0.27
20	98.03	3.67	13.47
21	92.09	-2.27	5.15
22	90.65	-3.71	13.76
23	91.64	-2.72	7.40
24	99.88	5.52	30.47
25	94.73	0.37	0.14
26	91.09	-3.27	10.69
27	94.65	0.29	0.08
28	98.51	4.15	17.22
29	94.53	0.17	0.03
30	96.3	1.94	3.76
31	94.85	0.49	0.24
32	91.11	-3.25	10.56
33	91.59	-2.77	7.67
34	97.61	3.25	10.56
35	91.02	-3.34	11.16
36	94.92	0.56	0.31
37	98.54	4.18	17.47
38	93.52	-0.84	0.71
39	97.78	3.42	11.70
40	99.77	5.41	29.27
41	92.02	-2.34	5.48
42	91.92	-2.44	5.95
43	90.76	-3.6	12.96
44	97.91	3.55	12.60
45	90.75	-3.61	13.03
46	92.61	-1.75	3.06
47	99.47	5.11	26.11
48	90.23	-4.13	17.06
49	90.41	-3.95	15.60
50	96.39	2.03	4.12
Sum	4718.01		438.85
Xbar	=4718.01/50 = 94.36
Standard deviation	2.96

HOW DO YOU FIND THESE CALCULATIONS: for Xbar and Xbar2 is there a formula in Excel?