This table shows the weight of suitcases checked in for a flight  

Weight(kg)  Frequency 
0 < w ≤ 5  2 
5 < w ≤ 10  11 
10 < w ≤ 15  25 
15 < w ≤ 20  18 
20 < w ≤ 25  13 
25 < w ≤ 30  11 
(a) draw a frequency polygon for the data  
(b)which class interval contains the median weight = 15 < w ≤ 20  
(c)all luggage is charged at £20 per suitcase a suitcase weighting over 20kg has an additional charge of£7.50 how much money is charged for all the luggage on this flight? 

= add all frequencies up = 80 =£20 per suitcase = 80 x 20 = 24 frequencies were over 20kg = 24 x 7.50 80 x20 = 1600 + 24 x 7.50 = 180 = £1780 
25  
f  

r  
e  
q  20  
u  
e  
n  
c  15  
y  
10  
5  
5  10  15  20  25  30  
0  weight kg 