The following sample data were recently collected in the course of conducting a randomized block analysis of variance. Based on these sample data, what conclusions should be reached about blocking effectiveness and about the means of the three populations involved? Test using a significance level equal to 0.05.

Block Sample 1 Sample 2 Sample 3 1 30 40 40 2 50 70 50 3 60 40 70 4 40 40 30 5 80 70 90 6 20 10 10