The purchasing department has analysed the number of orders placed by each
of the 5 departments in the company by type for this financial year as given in
the table below:

Order type Sales Purchase Production Accounts Maintenance Total
Consumables
Equipment
Special
Total
10
1
0
11
12
3
0
15
4
9
4
17
8
1
1
10
4
1
2
7
38
15
7
60
An error has been found in one of these orders.
Required:
(i) Determine the probability that the incorrect order was not for consumables. (2
marks)
(ii) Determine the probability that the incorrect order came from maintenance or
production. (2 marks)
(iii) Calculate the probability that the incorrect order was an equipment order from
purchase. (1 mark)
(c) (i) Under what conditions does P(A/B) = P(A)? (2 marks)
(ii) What is the addition rule of probability and for what type of events is it
valid?
(2 marks)
(iii) What is Bayes Theorem? (2 marks)