Question

a) The probability that a medical drug will cure a disease is 0.95 if the patient has the disease. The probability reduces to 0.10 if the patient doses not have the disease. If 70% of people in a selected community have the disease, find the probability that a person who has been cured actually had the disease.                               [6 marks]

b) A property sales agent estimates the probability of striking a deal will a client as follows:

Sale values (K’000)	4	4.5	5	5.5	6
Probability	0.14	0.26	0.30	0.20	0.10

I) Find the expected sales value.                                                                   [4 marks]

ii) Find the standard deviation of the sales

c) The following table shows, for a group of 12 production workers, the number of months of working experience on a particular process each of them had, and the number of defective items that they produced during a given week.

Worker	A	B	C	D	E	F	G	H	I	J	K	L
Experience(Months)	9	11	8	16	10	14	12	6	4	13	3	11
Number of rejects produced	24	18	26	14	21	16	22	24	36	20	30	23

You are required to:

I) calculate the coefficient of linear correlation for the data, and comment on the result.                                                                                                          [8 marks]

ii) Determine the coefficient of determination for the data, and explain its implication.

                                                                                                                    [4 marks]

iii) Determine the equation of the least squares regression line, and comments on the values of the coefficient and the constant.                                          

Answer 1