How long does it take to y from Denver to Atlanta on Delta Airlines? The table below shows 56 observations on fight times (in minutes) for the first week of March 2005.
(a) Use the grouped data formula to estimate the mean and standard deviation.
(b) Using the un- grouped data (not shown), the ungrouped sample mean is 161.63 minutes and the ungrouped standard deviation is 8.07 minutes. How close did your grouped estimates come?
(c) Why might fight times not be uniformly distributed within the second and third class intervals? (Source: www.bts.gov.)

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Flight Times DEN to ATL (minutes) DeltaAir From To frequency 140 150 160 170 180 150 160 170 180 190 25 24 4 Total 56