Statistics for Business: Decision Making and Analysis, 3rd Edition

12.3 Percentiles

The previous example uses a normal model to find a probability, the chance of choosing a diamond that costs more than $5,000. Such problems ask us to find the probability associated with being larger or smaller than some value. Other problems require working in the opposite direction that starts with the probability. Here’s an illustration.

Many types of packaging include a weight on the label. For example, a box of cereal might list the weight as 16 ounces. That’s seldom the exact weight. Automated packaging systems fill the boxes so quickly that there’s no time to weigh each one. Consequently, there’s variation in the weights. Most consumers are not going to complain if the box of cereal has more than 16 ounces, but they won’t ...