The following ‘less than’ cumulative frequency table shows the number of families according to their monthly electricity consumption.
Consumption (units) | Less than cumulative frequency
less than 100 | 12
less than 200 | 37
less than 300 | ___
less than 400 | 68
less than 500 | 80
It is also known that exactly 16 families consume between 300 and 400 units each month.
(i) Find the missing cumulative frequency for ‘less than 300’ units.
(ii) Hence determine the frequency of the 200–300 unit class.