toughest [Adjective] + problem [Noun]

Strength Strength Dispersion
A:
4
CHISQ:
4.46
AWT:
15,667,647
TTEST:
1.27
G2:
5.24
FAWT:
3.47
MI:
1.46
LOGLOG:
2.91
JD:
0.51
MI3:
5.46
DICE:
0.01
RANGE: