A store’s most requested shoe size is 8. Ordering nothing but size 8 would still disappoint most customers in the small example below. “Most common” is not the…
Two teams shorten their average completion times. Yet the organization’s average time more than doubles. That sounds like a spreadsheet mistake, but it can happen with perfectly consistent…
A traveler covers 24 miles at 30 mph, then another 24 miles at 60 mph. The two distances are equal, so it is tempting to average the speeds…
You have an 84% average before the final exam and want to finish the course with 88%. If the exam is worth 30% of the course grade, scoring…
Three observations can agree perfectly even when the process producing them is quite variable. A small sample may simply miss the part of the distribution that would change…
Convert a weather log from Celsius to Fahrenheit and its average changes. So does its standard deviation. Its variance changes by yet another factor, even though every entry…
Five deliveries take 3, 4, 5, 6, and 7 minutes. Their average time is 5 minutes, and their median is also 5 minutes. Now imagine that the last…
Two classes take the same test. In the smaller class, 95% pass. In the larger class, 45% pass. What percentage of all the students pass? The tempting answer…
