In ΔNOP, o = 4.6 inches, n = 5.2 inches and ∠N=21°. Find all possible values of ∠O, to the nearest 10th of a degree.

If the differences between the group means is large relative to the amount of variability in the scores, the group differences are probably significant. If, however, there is a lot of variability in the scores, then the difference between (or among) the group means will not seem so large, a non-significant difference.

So to summarize, it depends on the group. As there is no shown group, I can't determine what it would be.