Stat Test #3 Review: Answer Key
n  90
1.
x  40
  0.01
H 1 : p  0.6
H 0 : p  0.6
Use stat test #5
P  value    reject H 0
P-value= 0.001296
There is sufficient evidence to reject the claim that the population proportion of mortality is 0.6 at the 0.01
significance level. Therefore, the claim that it has dropped is true.
x  10.8 thousand
2.
s  0.6 thousand
Use stat test #2
n  36
  0.05
P-value= 0.00495
H 1 :   11.1 thousand
H 0 :   11.1 thousand
P  value   reject H 0
There is sufficient evidence to reject the claim that the population mean mileage is 11.1 thousand at the 0.05
significance level. Therefore, the claim that it is different is true.
3.
Student
Faculty
H 1 : p1  p 2
n  124
x  60
n  42
x  15
H 0 : p1  p 2 Use stat test #6
P-value= 0.7689
  0.10
P  value    reject H 0
There is sufficient evidence to reject the claim that the population proportion of students’ cars that are 4 years or
younger equals faculty cars that are 4 years or younger at the 0.10 significance level. Therefore, the claim that
the student proportion is higher is true.
4.
BQ
MC
x  4 .8
x  5 .2
s2
s  1.8
n  16
n  14
P-value= 0.5689
H 1 : 1   2
H 0 : 1   2
Use stat test #4
  0.05
P  value   Don' t reject H 0
There is insufficient evidence to reject the claim that there is no difference in population mean waiting times
between BQ and MC at the 0.05 significance level. Therefore, the claim of a significant difference is false.
5.
Input " before" in L1
Input " after" in L2
H 1 : 1   2
H 0 : 1   2
let : L3  L1  L2
P-value= 0.0236
Use stat calc 2: select data and let: “List:” be L3
P  value    reject H 0
There is sufficient evidence to reject the claim that there is no difference in population mean sales before and
after the consultant’s visit at the 0.05 significance level. Therefore, the claim of effectiveness is true.
6.
Pblm
1.
2.
3.
Interval
(0.342, 0.547)
(10.597, 11.003)
(-0.0428, .296)
4.
(-1.821, 1.0214)
5.
(-9.784, -.0963)
We are 95% confident that:
the population proportion mortality rate is between 34.2% and 54.7%.
the population mean mileage is between 10.597 and 11.003 thousand miles.
the difference in population proportion of car ages (students v. faculty) is between:
-4.28% and 29.6%.
the difference in population mean waiting times at the 2 establishments is between
-1.821 and 1.0214 minutes.
the difference in net sales before and after consultation is between -9.784 & -0.0963
sales.