Question 1181706
The third class is 100-109 mm, and the fourth class is 110-119 mm.

The class boundary between these two classes is the midpoint between the upper limit of the third class and the lower limit of the fourth class.

Class boundary = (109 + 110) / 2 = 219 / 2 = 109.5 mm

So, the class boundary between the third and fourth classes is 109.5 mm.