Correction v Calibration
Duchess_Driver your confusing "correction" for "calibration"
Having found the Corrected Air Speed (CAS) which is the question: then by reference to the actual aircraft manual Calibration Table or graph if applicable: you then interpolate to discover any "position error" but that does not change CAS.
The question does not include a calibration table/graph so cannot be included in calculating the final IAS for the answer.
We all learn in building blocks and I'm sure calibration will be covered in a later unit.
F