The number of treads in a flight is equal to
- ARisers in the flight
- BRisers plus one
- CRisers minus oneCorrect
- DNone of the above
Solution
Concept
Relation between treads and risers in flight
Formula
Treads = Risers - 1
Step-by-step solution
1. A flight of stairs consists of a series of continuous steps between two landings. 2. Each step consists of one vertical riser and one horizontal tread surface. 3. Since the upper landing functions as the top step tread, the total number of treads equals Risers minus one. Answer: C
Explanation
In staircase design, a flight consists of alternating horizontal treads and vertical risers. Because the top riser leads directly onto a landing floor surface, there is always one less tread surface than the total number of risers in that flight. Thus, the relationship is strictly defined as treads equal to risers minus one.
Why the other options are wrong
A) Treads are one fewer than risers because the top landing acts as the final tread. B) Adding one to the number of risers incorrectly increases the tread count. D) Option C is correct as treads always equal risers minus one.
Shortcut
Number of Treads = Risers - 1.
Common mistake
Adding one to the number of risers instead of subtracting one to determine the number of treads.
Correct answer: C) Risers minus one