The Greenland company was conducting research to compare the proficiency of three training programs, Green 1, Green 2 and Green 3, in training assemblers of a piece of agricultural equipment. Twenty-one employees were randomly picked to the three programs. After completion of the programs, each person was required to assemble pieces of the equipment, and the average length of time required to complete the assembly was recorded. The results are shown in tables below ("?" represents missing value).

	Average	Variance	Standard deviation	Sum(EX)	Sample size
Green 1	?	59.8065	7.7335	195.5	?
Green 2	25.0938	?	9.722	200.75	8
Green 3	24.9583	111.0104	10.5361	149.75	6

1. Can Greenland company's manager infer at the 99% confidence level that there are differences in the average assembly times for people trained by the three programs? (Assume normal distributions with equal variances.)
2. Estimate with 5% significance level the differences in mean assembly times between persons trained by programs Green 1 and Green 3. (Assume normal distributions with equal variances.)