An auditor for a hardware store chain wished to compare the efficiency of two different auditing techniques. To do this he selected a sample of nine store accounts and applied auditing techniques A and B to each of the nine accounts selected. The number of errors found in each of techniques A and B is listed in the table below
|
Errors in A
|
Errors in B
|
|
25
|
11
|
|
28
|
17
|
|
26
|
19
|
|
28
|
17
|
|
32
|
34
|
|
30
|
25
|
|
29
|
29
|
|
20
|
21
|
|
25
|
30
|
Select a 90% confidence interval for the true mean difference in the two techniques