Question

The class marks of a frequency distribution are 47, 52, 57, 62, 67, 72, 77. Determine the (i) class size (ii) class limits with respect to the class mark 52 (iii) true class limits for class mark 52.

Answer 1

Class marks of the frequency distribution: 47, 52, 57, 62, 67, 72, 77
(i) Class size = Length of each class
= 52 $-$ 47
= 5
(ii) $\frac{\mathrm{Class}\mathrm{size}}{2}=\frac{5}{2}=2.5$
Class limits with respect to the class mark 52 are (52 $-$ 2.5) and (52 + 2.5), i.e., 49.5 and 54.5.

(iii) Classes are in the exclusive form and in the exclusive form, the upper and lower limits of a class are known as true upper limit and true lower limit, respectively.

Therefore, the true class limits are 49.5 and 54.5.