(i) 10% represents 100 people.
Therefore 20% represents = 100 x 20/10 = 200 pepole
Hence, 200 people were surveyed.
(ii) Light music is liked by the maximum number of people.
(iii) CD’s of classical music = 10 x 1000/100 = 100
CD’s of semi-classical music = 20 x 1000/100 = 100
CD’s of light music = 40 x 1000/100 = 400
CD’s of folk music = 30 x 1000/100 = 300