The frequency distribution below shows the distribution for checkout time (in minutes) in UMUC MiniMart between 3:00 and 4:00 PM on a Friday afternoon.
|
Checkout Time (in minutes)
|
Frequency
|
|
1.0 - 1.9
|
6
|
|
2.0 - 2.9
|
7
|
|
3.0 - 3.9
|
2
|
|
4.0 - 4.9
|
3
|
|
5.0 - 5.9
|
2
|
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What percentage of the checkout times was at least 4 minutes?
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Calculate the mean of this frequency distribution.
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Calculate the standard deviation of this frequency distribution.
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Assume that the smallest observation in this dataset is 1.2 minutes. Suppose this observation were incorrectly recorded as 0.12 instead of 1.2. Will the mean increase, decrease, or remain the same? Will the median increase, decrease or remain the same? Explain your answers.