A process improvement team is in the Measure phase of improving a call center$$s operations. They are working on reducing the on$-$hold time customers experience before talking to an associate. The current target is $40$ seconds. Historically, the average on$-$hold time is $2\mathrm{.}3$ minutes with a standard deviation of $0\mathrm{.}58$ min. The team wants to be able to determine the average on$-$hold time within $+/-0\mathrm{.}05$ min. The call center averages $3360$ calls per week. The call center operates $24$ hours per day, $365$ days per year. They have developed and implemented a data collection plan which calls for measuring on$-$hold time for $1$ week over two $60$ minute periods starting at $11$:$30$am and $6$:$30$pm each day when call volume is heaviest $($average of $38$ calls per hour$).$ The results are plotted in a histogram and an X and Moving Range chart $($below$).$

What is the most reasonable conclusion to be drawn from these data?