Statistics: set 5
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A hypothetical district has 180,000 residents and an area of 450 square kilometres. What is the population density (a relative indicator of intensity)?
At a bank branch an operator serves 60 customers a day on average, with a standard deviation of 8 customers. Yesterday the operator served 76 customers. What is the standardized deviation (z-score) of yesterday's result?
A courier service recorded order delivery times (minutes) over eight days: 12, 4, 19, 7, 15, 9, 6, 14. Find the interquartile range (Q3 − Q1), calculating the quartiles as the medians of each of the two equal halves of the ordered series.