Continuous method:

Stage 1	Stage 2	Stage 3	Stage 1	Stage 2	Stage 3	Stage 1	Stage 2	Stage 3
12.12	11.92	08.74	11.99	15.60	10.08	12.67	15.38	08.96
10.23	09.65	14.76	21.45	10.25	11.49	09.31	14.49	14.63
09.49	09.78	12.27	09.66	10.85	14.08	09.73	10.52	11.99
11.22	10.12	10.15	12.34	15.23	10.24	09.63	14.23	10.02
09.08	10.98	17.94	14.83	12.45	16.35	14.40	12.19	14.09
10.75	12.87	11.32	11.84	15.37	12.59	11.15	11.79	14.50
14.75	28.14	11.85	23.86	12.94	13.01	11.40	11.38	12.42
11.53	10.28	13.29	10.41	13.17	36.29	11.32	14.50	13.36
11.15	24.86	15.23	09.80	12.46	14.33	11.10	15.41	11.70
11.75	18.37	10.10	12.43	13.53	14.07	14.23	11.53	10.45

b. determine the required number of observations for 1 percent precision and confidence level of 68%.