Question

In the tables given below, class-mark and frequencies is given.

Construct the frequency tables taking inclusive and exclusive classes.

Class mark	Frequency
22	6
24	7
26	13
28	4

Answer 1

Let the lower class limit and upper class limit of the class mark 22 be x and y respectively.

Class mark = \(\frac{Lower\, class\, limt \,+\,Upper\, class\, limt \,}{2}\)

\(\therefore\) \(22 = \frac{x\,+\,y}{2}\)

∴ x + y = 44 …(i) 

Here, class width = 24 – 22 = 2

 But, Class width = Upper class limit – Lower class limit 

∴ y – x = 2 

∴ -x + y = 2 …. (ii) 

Adding equations (i) and (ii),

x + y = 44 

– x + y= 2 

2y = 46 

∴ y = 23 

Substituting y = 23 in equation (i), 

∴ x + 23 = 44 

∴ x = 21 

∴ class with class-mark 22 is 21 – 23 

Similarly, we can find the remaining classes 

∴ Frequency table taking inclusive and exclusive classes.