13.6 Is there an interaction? Each of the following tables gives means for a two-way ANOVA. Make a plot of the means with the levels of Factor A on the x axis. State whether or not there is an interaction, and if there is, describe it.

	Factor A
Factor B	1	2	3
1	11	21	31
2	6	11	16

	Factor A
Factor B	1	2	3
1	10	5	15
2	20	15	25

	Factor A
Factor B	1	2	3
1	10	15	20
2	15	20	25

	Factor A
Factor B	1	2	3
1	10	15	20
2	20	15	10