Solution:
From the given data, the class boundary between the fifth and sixth classes is thus evaluated as follows:
step 1: Determine the upper class limit of the fifth class.
The upper class limit of the fifth class is

step 2: Determine the lower class limit of the sixth class.
The lower class limit of the sixtth class is

step 3: Evaluate the class boundary between the fifth and sixth classes.
Thus, we have
