StatisticsdrillEmpirical rule: 68-95-99.7
A statistics problem from Statisticsdrill. Solve it with one answer box, with a fresh sample on every attempt and the worked steps and spreadsheet function in the answer, and it is checked the moment you submit.
The task
Scores on a certification exam are roughly bell-shaped with a mean of 68 points and a standard deviation of 6. Using the empirical rule (68-95-99.7), about what percent of values fall between 50 and 56 points? Give the percent rounded to 2 decimal places.
What this problem teaches
The empirical rule is a rounded version of the normal curve, so the exact normal area differs slightly.
A hint if you get stuck
Turn each limit into a number of standard deviations from the mean. The rule puts 34% between the mean and 1 SD, 47.5% out to 2 SD and 49.85% out to 3 SD, on each side.
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