Sometimes an extraordinary factor affects data that would otherwise be normally distributed. A coin, for example, may be somehow weighted unevenly so that heads tends to come up more frequently than tails. In such a case, the data set could have a distribution that is skewed, an asymmetric curve where one end stretches out further than the other end.
Zoology The bar graph gives the weights of a population of female brown bears. The red curve shows how the weights are normally distributed about the mean, 115 kg. Approximately what percent of female brown bears weigh between 100 and 129 kg?
How do you find this percent?
The percents for each bar are based on the same sample population of bears. You can add the percents.
Estimate and add the percents for the intervals 100–109, 110–119, and 120–129.
23 + 42 + 23 = 88
About 88% of female brown bears weigh between 100 and 129 kg.
When data are normally distributed, you can sketch the graph of the distribution using the fact that a normal curve has a symmetric bell shape.