Question

Boundaries with the inclusive class interval are shown in the table below.

Limits	Boundaries
10.5 -14.5	10 - 15
?	15 - 20
20.5 - 24.5	20 - 25

What is the class interval of Group 2?

• A. 14.5 - 19.5
• B. 14.5 - 18.5
• C. 15.5 - 19.5
• D. 16.5 - 19.5

Answer 1

The correct option is C 15.5 - 19.5

Let,
Lower limit of class (Group 2) = x
Upper limit of class (Group 2) = y

Average of upper limit of first class and lower limit of second class becomes the upper boundary of the first class.

15 = $\frac{14.5+x}{2}$

x = 15.5

Similarily,

20 = $\frac{20.5+y}{2}$

y = 19.5