9.The total population consisting of children, adults and old persons in 900 K. If in a pie-diagram, the’ angles subtended by them at the centre are 100°, 180″ and 80° respectively, what will be their] respective numbers ?

The correct answer is (a).

The total population is 900 K. The angles subtended by children, adults and old persons at the centre are 100°, 180° and 80° respectively. The ratio of these angles is 100:180:80 = 5:9:4. The respective numbers of children, adults and old persons are 5/18 * 900 = 250 K, 9/18 * 900 = 450 K and 4/18 * 900 = 200 K.

Option (b) is incorrect because the total number of people in option (b) is 980 K, which is not equal to the total population of 900 K.

Option (c) is incorrect because the ratio of the numbers of people in option (c) is 2:4:5, which is not equal to the ratio of the angles subtended by them at the centre.

Option (d) is incorrect because the answer is not given in any of the options.