Question

Test to determine if the average cell phone bill differs when compared to the same programs and same areas. A random sample of cell phone bills (in dollars) from four companies is reported below a = .01

Verizon 100 125 105 100 110

Sprint 100 130 90 120 90

At and T 90 90 90 100 120

T Mobile 100 100 110 90 80

Answer 1

Null hypothesis ( H0 ) : All means are equal

i.e .,

Alternative hypothesis ( Ha ) : Atleast one of the is different

For the given data using Anova single factor in Excel we get output as

Anova: Single Factor
SUMMARY
Groups	Count	Sum	Average	Variance
verizon	5	540	108	107.5
sprint	5	530	106	330
At and T	5	490	98	170
T mobile	5	480	96	130
ANOVA
Source of Variation	SS	df	MS	F	P-value	F crit
Between Groups	520	3	173.3333	0.940113	0.444386	5.292214
Within Groups	2950	16	184.375
Total	3470	19

Decision :

p value > 0.01

i .e ., 0.444386 > 0.01

So fail to reject H0

Conclusion : At alpha = 0.01 l.o.s there is no evidence to conclude that the average cell phone bill differs when compared to the same programs and same areas.