Here's how to solve the problem:

• Understanding the terms:

  • RL (Reduced Level): The height of a point above a datum (reference level, often mean sea level).
  • Backsight (BS): A reading taken on a point of known elevation (benchmark).
  • Inverse Staff Reading: A reading taken with the staff held upside down, typically on a roof or overhead feature.

• Calculation Steps:

  1. Height of Instrument (HI): The height of the level instrument above the datum.

     • HI = RL of Benchmark + Backsight
     • HI = 100.00 m + 3.25 m = 103.25 m

  2. RL of Roof Station: When using an inverse staff, the reading adds to the HI to get the roof's RL.

     • RL of Roof Station = HI + Inverse Staff Reading
     • RL of Roof Station = 103.25 m + 1.25 m = 104.50 m

Therefore, the RL of the roof station is 104.50 m. This falls within the requested range of 104 to 105.

Final Answer: 104.50