Answer:
[tex]\frac{3}{8} inches[/tex]
Explanation:
the variations in riser height or tread depth should not be grater than [tex]\frac{3}{8} inches[/tex] that is equal to 9.5 mm but the maximum riser height should be the [tex]\frac{81}{4} inch[/tex] but variation in riser height should not exceed to [tex]\frac{3}{8} inches[/tex]. The minimum riser height should be 7 inches which is equal to the 178 mm