While his wife getting help on a CD, a patron recorded the wait time (in minutes) for customers in two separate lines as

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While his wife getting help on a CD, a patron recorded the wait
time (in minutes) for customers in two separate lines as follows:
Line 1: 6.5, 7.7, 7.1, 6.6, 7.7, 6.8, 7.4, 7.3, 6.7, 7.7, Line 2:
5.4, 6.2, 7.7, 5.8, 10.0, 7.7, 9.3, 8.5, 4.2, 6.7 Many banks once
required that customers wait in separate lines at each teller's
window, but most have now changed to one single main waiting line.
The mean waiting time did not change, because the waiting line
configuration does not affect the efficiency of the tellers. Use
this observational study to help you determine why did they make
that change.
How did this study motivate the change?