Answer:
H0 : μ = 3.2
H1 : μ > 3.2
1.982
We fail to reject the Null ;
There is no significant evidence to conclude that the mean replacement time under the new contractor takes longer than the usual average time.
Explanation:
μ = average time taken by the previous contractor. ; μ = 3.2
H0 : μ = 3.2
H1 : μ > 3.2
Sample size, n = 12 ;
X = 6.2 7.1 5.4 5.5 7.5 2.6 4.3 2.9 3.7 0.7 5.6 1.7
xbar = Σx / n = 53.2 / 12 = 4.43
Standard deviation, s ; using a calculator :
s = 2.15
B.)
The test statistic :
(xbar - μ) ÷ (s / sqrt(n))
(4.43 - 3.2) ÷ (2.15 / sqrt(12))
1.23 ÷ 0.62065
= 1.982
C.)
Decision Region :
If Pvalue < α ; Reject the null
α = 0.05
Pvalue :
P(x < 1.982) = 0.9762
0.9762 > 0.05 ; Hence, we fail to reject the Null
There is no significant evidence to conclude that the mean replacement time under the new contractor takes longer than the usual average time.