You are writing a procedure to characterize ⁹⁰Sr/⁹⁰Y contamination in a legacy facility. Gas proportional probes that measure 10cm x 15cm will be used to scan floors and walls. The 150 cm² area probe will be moved along its 10cm axis. What scan speed must be maintained in order to meet a total contamination (fixed plus removable) MDA of 1000 dpm/100cm² ? Assume that the detector efficiency is 0.35 cpm/dpm and the probe background is 500 cpm. State any other assumptions and show all calculations.