sTEm–at-Work Puzzle #39 (Answer)

The Problem: sTEm puzzle #39

Analysis
sTEm puzzle #39 provides an opportunity to present the characteristics of single and double stage pumps. Two stage pumps will bring the pressure to a lower value than a single stage pump. The data below provides the summary of each pump's performance. The graphic indicates that the two stage pump does not "pump" a vacuum as low as the single stage pump can accomplish. One reason for this inconsistency is that the plots are indeed mislabeled.  
                                                                                                                
Solution
Does the technician suspect that the performance data recorded below is missed labeled. YES