Hand tool proportions in finishing works: the typical ratio of length to breadth of a wooden float used for plaster or concrete finishing is approximately which of the following?

Introduction / Context:
A wooden float is a simple, ubiquitous finishing tool used to dress plaster and to bring mortar to a uniform texture on concrete surfaces. Standardized proportions improve handling, surface flatness, and worker ergonomics.

Given Data / Assumptions:

• We refer to a conventional hand float (rectangular wooden board with handle).
• Practical sizes balance coverage per stroke with manageable weight and control.
• Common site sizes range in the ballpark of a few hundred millimetres in length with modest breadth.

Concept / Approach:
Field practice often uses floats in the approximate size range of about 325–450 mm length and 50–70 mm breadth for general finishing. This yields a length-to-breadth ratio broadly around 6:1 to 7:1. Such proportions allow the tool to bridge minor undulations while remaining easy to wield with one hand.

Step-by-Step Solution:
Relate typical dimensions (e.g., 390 mm × 60 mm) → L/B ≈ 6.5.Check alternatives: 4.5 is relatively squat; 8.5 becomes unwieldy for general use.Therefore, select the mid-range practical ratio ≈ 6.5.

Verification / Alternative check:
Trade catalogs and site practice often list floats with L/B between about 6 and 7; specialty floats (bull floats) differ and are not in scope.

Why Other Options Are Wrong:

• 4.5/5.5: too short for efficient coverage and bridging.
• 7.5/8.5: increasingly unwieldy for hand control in tight interiors.

Common Pitfalls:
Confusing hand floats with larger bull floats or magnesium floats used for slabs; assuming one-size-fits-all without considering ergonomics.

Final Answer:
6.5