The following series relates to the daily income of workers employed in a firm. Compute (a) highest income of lowest 50% workers (b) minimum income earned by the top 25% workers and (c) maximum income earned by lowest 25% workers.
Daily Income (in Rs)  10 – 14  15 – 19  20 – 24  25 – 29  30 – 34  35 – 39 
Number of workers  5  10  15  20  10  5 
(Hint: Compute median, lower quartile and upper quartile)
Daily Income (in Rs) Class Interval  No. of Workers (f)  Cumulative frequency (CF) 
9.5 – 14.5  5  5 
14.5 – 19.5  10  15 
19.5 – 24.5  15  30 
24.5 – 29.5  20  50 
29.5 – 34.5  10  60 
34.5 – 39.5  5  65 


(a) Highest income of lowest 50% workers
32.5^{th} item lies in the 50^{th} cumulative frequency and the corresponding class interval is 24.5 – 29.5.
(b) Minimum income earned by top 25% workers
In order to calculate the minimum income earned by top 25% workers, we need to ascertain Q_{3}.
48.75^{th} item lies in 50^{th} item and the corresponding class interval is 24.5 – 29.5.
(c) Maximum income earned by lowest 25% workers
In order to calculate the maximum income earned by lowest 25% workers, we need to ascertain Q_{1}.
16.25^{th} item lies in the 30^{th} cumulative frequency and the corresponding class interval is 19.5 – 24.5