Question 75The class mark and frequency of a data is given in the graph. From the graph, Find:(a) the table showing the class interval and frequency.(b) the mean

Question

Accepted Answer

(a) Class marks : 13, 15, 17, 19, 21, 23.

Difference between two consecutive class marks = 15 - 13 = 2.

Lower limit of class = Class mark - 1

Upper limit of class = Class mark + 1

Class	Frequency
12 - 14	8
14 - 16	2
16 - 18	3
18 - 20	4
20 - 22	5
22 - 24	6

(b)

Class	Class mark (x)	Frequency (f)	fx
12 - 14	13	8	104
14 - 16	15	2	30
16 - 18	17	3	51
18 - 20	19	4	76
20 - 22	21	5	105
22 - 24	23	6	138
Total		Σf = 28	Σfx = 504

Mean = $\dfrac{Σfx}{Σf} = \dfrac{504}{28}$ = 18.

Hence, mean = 18.

Short Answer Questions 1 — Question 26

Question 75