Question

Write the class size and class limits in each of the following:
(i) 104, 114, 124, 134, 144, 154, and 164
(ii) 47, 52, 57, 62, 67, 72, 77, 82, 87, 92, 97 and 102
(iii) 12.5, 17.5, 22.5, 27.5, 32.5, 37.5, 42.5, 47.5

Answer 1

(i) 104, 114, 124, 134, 144, 154 and 102
    Class size = 114 – 104 = 10

Class mark	Lower class limit	Upper class limit	Class limit
104	104-(10/2)=99	104+(10/2)=109	99-109
114	114-(10/2)=109	114+(10/2)=119	109-119
124	119	129	119-129
134	129	139	129-139
144	139	149	139-149
154	149	159	149-159
164	159	169	159-169

(ii) 47, 52, 57, 62, 67, 72, 79, 82, 87, 92, 97, 1102
    Class size = 52-47 = 5 

Class mark	Lower class limit	Upper class limit	Class limit
47	47·(5/2)=44·5	47+(5/2)=49·5	44·5-49·5
52	49.5	54.5	49·5-54·5
57	54.5	59·5	54·5-59·5
62	59·5	64·5	59·5-64·5
67	64·5	69·5	64·5-69·5
72	69·5	74·5	69·5-74·5
77	74·5	79·5	74·5-79·5
82	79·5	84·5	79·5-84·5
87	84·5	89·5	84·5-89·5
92	89·5	94·5	89·5-94·5
97	94·5	99·5	94·5-99·5
102	99·5	104·5	99·5-104·5

(iii) Class size =17.5-12.5=5

Class mark	Lower class limit	Upper class limit	Class limit
12·5	12·5-(5/2)=10	12·5+(5/2)=15	10-15
17·5	17·5-2·5=15	17·5+2·5=20	15-20
22·5	22·5-2·5=20	22·5+2·5=25	20-25
27·5	27·5-2·5=25	27·5+2·5=30	25-30
32·5	32·5-2·5=30	32·5+2·5=35	30-35
37·5	37·5-2·5=35	37·5+2·5=40	35-40
42·5	42·5-2·5=40	42·5+2·5=45	40-45
47.5	47·5-2·5=45	47·5+2·5=50	45-50