Download Hypothesis Test for One Population mean

Hypothesis Test for One Population Mean
Example The owners of a large real estate agency believe that a slow economy has lowered the selling prices of
homes below last year’s average of $102,000. A random sample of the selling prices of 18 homes sold
(expressed in thousands of dollars) reported the following figures:
105.0 104.0 81.0
84.0 92.0 92.9
128.0 74.0
108.0 85.9
111.0 86.9 87.9
115.0 134.0 84.5
87.0
91.9
Do the data provide sufficient evidence to conclude that the average selling price of homes sold by this firm has
decreased. Conduct hypothesis test using =.01.
Entering the data in Minitab:
Selling price
105.0
104.0
.
.
91.9
Assessing Reasonableness of Normality Assumption
Using Minitab
Minitab Commands for Normal Probability Plot: > stat > basic statistics > normality test > variable selling
price > OK
Minitab Commands for HISTOGRAM: > Graph > Histogram > simple > OK > graph variable selling price
> OK
Probability Plot of sell price
Histogram of sell price
Normal
7
99
Mean
StDev
N
AD
P-Value
95
90
6
5
Frequency
Percent
80
97.39
16.57
18
0.683
0.062
70
60
50
40
30
20
4
3
2
10
1
5
1
50
60
70
80
90
100
sell price
110
120
130
140
0
70
80
90
100
sell price
110
120
130
Conducting Hypothesis Test Using Minitab
Minitab Commands: > stat > basic statistics > 1-sample t > put cursor in the box and double click on
selling price > click on perform hypothesis test > hypothesized mean 102 > options > alternative mean less
than hypothesized mean
Minitab Output:
Test of mu = 102 vs < 102
Variable
C10
N
18
Mean
97.3889
StDev
16.5696
SE Mean
3.9055
95%
Upper
Bound
104.1829
T
-1.18
P
0.127