IN order to compare the durability of four different brands of golf balls, five randomly selected balls from each brand and places each ball into a machine that exerts the force produced by a 250-yard drive. The results are given in figure 12.6 Test for statistically significant differences between the treatment means malpha, mbest, mcentury, and mdivot. Set a = .05

Golf Ball Durability Test Results	12.6	groups	count	sum	average	variance
Alpha	Best	Century	Divot	Alpha	5	1268	253.6	609.3
281	270	218	364	Best	5	1532	306.4	740.3
220	334	44	302	Century	5	1209	241.8	469.7
274	307	225	325	Divot	5	1683	336.6	605.3
242	290	273	337
251	331	246	355	tukey simulatneous comparison t-values (d.f. = 16)
Century	Alpha	Best	Divot
241.8	253.6	306.4	336.6
century	241.8
alpha	253.6	0.76
best	306.4	4.15	3.39
divot	336.6	6.09	5.33	1.94
Critical values for experimental error rate:
0.05	2.86
0.01	3.67
ANOVA
Source of Variation	SS	df	MS	F	P-value	F crit
Between groups	29860.4	3	9953.467	16.420798	3.85E-05	3.238872
Within groups	9698.4	16	606.15
Total	39558.8	19