(a) Sector angle represented by the officers:
Total number of officers = 240
Clerks = \(\frac{78}{240} \times 360° = 117°\)
Drivers = \(\frac{36}{240} \times 360° = 54°\)
Typists = \(\frac{44}{240} \times 360° = 66°\)
Messengers = \(\frac{52}{240} \times 360° = 78°\)
Others = \(\frac{30}{240} \times 360° = 45°\)

(b)

Marks (x)	4	5	6	7	8	9	Total
No of candidates (f)	5	8	5	6	4	2	30
\(fx\)	20	40	30	42	32	18	182

Mean score = \(\frac{\sum fx}{\sum f}\)
= \(\frac{182}{30}\)
= \(6.067\) marks \(\approxeq\) 6 marks to the nearest whole number.