Question

Find the class boundaries and class marks of the following classes:
55 - 59, 60 - 64, 65 - 69, 70 - 74, 75 - 79, 80 - 84, 85 - 89, 90 - 94 and 95 - 99.

Answer 1

For the class 55 - 59,
The actual lower limit = 55 - 0.5 = 54.5
The actual upper limit = 59 + 0.5 = 59.5
∴ The class boundaries are 54.5 and 59.5

∴ The class mark = `(1)/(2)(54.5 + 59.5)` = 57

Similarly calculating for the other classes we get the following table:

Class	Class Boundaries	Class Mark
55 - 59	54.5 - 59.5	57
60 - 64	59.5 - 64.5	62
65 - 69	64.5 - 69.5	67
70 - 74	69.5 - 74.5	72
75 - 79	74.5 - 79.5	77
80 - 84	79.5 - 84.5	82
85 - 89	84.5 - 89.5	87
90 - 94	89.5 - 94.5	92
95 - 99	94.5 - 99.5	97