(i) The number of eldest teacher = 1
youngest teachers in the school = 2
(ii) 35-40 age group teachers are more in the school.
50-55 age group teachers are least.
(iii) Size of the classes = 5 years
(iv) Class marks of the classes = average of class intervals = 32.5, 40, 47.5, 55, 62.5, 70, 77.5