Use the table given below to find :

(a) The actual class limits of the fourth class.

(b) The class boundaries of the sixth class.

(c) The class mark of the third class.

(d) The upper and lower limits of the fifth class.

(e) The size of the third class.

Class Interval	Frequency
30 - 34	7
35 - 39	10
40 - 44	12
45 - 49	13
50 - 54	8
55 - 59	4

(i) The actual class limits of the fourth class is 44.5-49.5.

(ii) The class boundaries of the sixth class is 54.5-59.5.

(iii) The class mark of the third class

$= \dfrac{40 + 44}{2}\\[1em] = \dfrac{84}{2}\\[1em] = 42$

(iv) The upper and lower limits of the fifth class (50-54) is 54 and 50, respectively.

(v) Interval of third class = 40-44

The size of class = Upper limit - lower limit + 1

The size of third class = 44 - 40 + 1

= 4 + 1

= 5

Hence, the size of third class is 5.